BORON TRICHLORIDE 1
well as the reaction temperature and time. The transformation of
Boron Trichloride1
(-)-²-hydrastine (1) to (-)-cordrastine II is efficiently achieved
by selective cleavage of the methylenedioxy group in prefer-
BCl3
ence to aromatic methoxy groups.5 The demethylation of (-)-
ć%
2-O-methyl-(-)-inositol in dichloromethane proceeds at -80 C
[10294-34-5] BCl3 (MW 117.17)
without cleavage of a tosyl ester group.6 Methyl glycosides are
ć%
InChI = 1/BCl3/c2-1(3)4 converted into glycosyl chlorides at -78 C without effecting ben-
InChIKey = FAQYAMRNWDIXMY-UHFFFAOYAQ zyl and acetyl protecting groups.7
OR MeO OR OR
(Lewis acid capable of selective cleavage of ether and acetal pro-
tecting groups; reagent for carbonyl condensations; precursor of
MeO CHO Me CO2Me C
organoboron reagents)
O
OMe OHC OMe R'O
ć% ć%
Physical Data: bp 12.5 C; d 1.434 g cm-3 (0 C).
R = Me H; R = Me H; (a) R = Me H, R' = Me;
Solubility: sol saturated and halogenated hydrocarbon and aro-
81%, rt, 5 min 78%,  80 °C 80%, rt, 0.5 h
matic solvents; solubility in diethyl ether is approximately 1.5
(b) R, R' = Me H;
ć% ć%
Mat 0 C; stable for several weeks in ethyl ether at 0 C, but
97%, rt, 8 h
dec by water or alcohols.
CH2CH=CMe2 RO
Form Supplied in: colorless gas or fuming liquid in an ampoule;
MeO
O Me
NMe
BCl3·SMe2 complex (solid) and 1 M solutions in dichloro-
R'O
methane, hexane, heptane, and p-xylene are available.
Handling, Storage, and Precautions: a poison by inhalation
O
RO O
and an irritant to skin, eyes, and mucous membranes. Reacts OMe
O
exothermically with water and moist air, forming toxic and OMe
corrosive fumes. Violent reaction occurs with aniline or phos- (1)
phine. All operations should be carried out in a well-ventilated
R = Me H; R, R' =  CH2 H;
fume hood without exposure to the atmosphere. The gas can be 81%, rt, 6 h
90%, rt, 5 min
collected and measured as a liquid by condensing in a cooled
Scheme 1 Demethylation of aromatic ethers by BCl3 in CH2Cl2
centrifuge tube and then transferred to the reaction system by
distillation with a slow stream of nitrogen. One of the difficulties with the use of BCl3 arises from its ten-
dency to fume profusely in air. The complex of BCl3 with dimethyl
sulfide is solid, stable in air, and handled easily. By using a two-
ć%
to fourfold excess of the reagent in dichloroethane at 83 C, aro-
Original Commentary
matic methoxy and methylenedioxy groups can be cleaved in good
yields.8
Norio Miyaura
Another application of BCl3 is for the cleavage of highly hin-
Hokkaido University, Sapporo, Japan
dered esters under mild conditions. O-Methylpodocarpate (2) and
ć%
methyl adamantane-1-carboxylate are cleaved at 0 C.9 The highly
Cleavage of Ethers, Acetals, and Esters. Like many other
selective displacement of the acetoxy group in the presence of
Lewis acids, BCl3 has been extensively used as a reagent for the
other potentially basic groups in 2-cephem ester (3) provides the
cleavage of a wide variety of ethers, acetals, and certain types of
corresponding allylic chloride. On the other hand, treatment of (3)
esters.2 Ether cleavage procedures involve addition of BCl3, ei-
with an excess of BCl3 results in the cleavage of the acetoxy and
ć%
ther neat or as a solution in CH2Cl2, to the substrate at -80 C.
t-butyl ester groups.10
The vessel is then stoppered and allowed to warm to rt. Whereas
the complexes of BCl3 with dimethyl ether and diethyl ether are
OMe
rather stable at rt, they decompose to form ROBCl2 or (RO)2BCl
ć%
with evolution of alkyl chloride upon heating to 56 C.1 Diaryl
Me
ethers are unreactive. Mixed dialkyl ethers are cleaved to give
PhCH2CONH S
the alkyl chloride derived from C O bond cleavage leading to
N
the more stable carbenium ion. The transition state is predomi-
CH2X
O
nantly SN1 in character, as evidenced by partial racemization of
Me CO2R CO2R
chiral ethers1,2 and the rearrangement of allyl phenyl ethers to o-
(2) (3)
allylphenols.3 BCl3 can be used for the deprotection of a variety of
R = Me H; 90% (1) R = t-Bu, X = OAc Cl; 64%
methoxybenzenes including hindered polymethoxybenzenes and
BCl3, CH2Cl2, 0 °C BCl3 (1 equiv), CH2Cl2,  5 °C
peri-methoxynaphthalene.1,2,4 When methoxy groups are ortho
(2) R = t-Bu H, X = OAc OH; 68%
to a carbonyl group, the reaction is accelerated by the forma-
BCl3 (3 equiv), CH2Cl2, rt
tion of a chelate between boron and the carbonyl oxygen atom
(Scheme 1).4a-c
The reagent is less reactive than Boron Tribromide for ether Tertiary phosphines are cleaved at the P C bond to give
cleavage; however, the type and extent of deetherification can diphenylphosphine oxides. Workup with Hydrogen Peroxide pro-
be more easily controlled by the ratio of substrate to BCl3 as vides diphenylphosphinic acids (eq 1).11
Avoid Skin Contact with All Reagents
2 BORON TRICHLORIDE
1. BCl3
OH O
HO
0 °C rt H2O2
1. MeN=C=O
Ph2PCH2XMe Ph2P(O)H Ph2P(O)OH (1)
BCl3, CH2Cl2, "
NHMe
2. H2O
(6)
X = O, S
2. H3O+
MeO
MeO
75%
Condensation Reactions. Boron trichloride converts ketones
Aldehydes and ketones condense with ketene in the pres-
ć%
into (Z)-boron enolates at -95 C in the presence of Diisopropy-
ence of 1 equiv of boron trichloride to give Ä…,²-unsaturated acyl
lethylamine. These enolates react with aldehydes with high syn
chlorides.22 Aryl isocyanates are converted into allophanyl chlo-
diastereoselectivity (eq 2).12 A similar condensation of imines
rides, which are precursors for industrially important 1,3-diazeti-
with carbonyl compounds also provides crossed aldols in reason-
dinediones (eq 7).23
able yields.13 The reaction was extended to the asymmetric aldol
condensation of acetophenone imine and benzaldehyde by using
O
isobornylamine as a chiral auxiliary (48% ee).14
pyridine
BCl3
PhN=C=O (7)
PhNHCON(Ph)COCl PhN NPh
BCl2
rt
O O O OH toluene
95%
0 °C
PhCHO
BCl3
O
70%
Ph
EtN(i-Pr)2 81%
CH2Cl2,  95 °C
(4) syn:anti = 93:7
(2) Synthesis of Organoboron Reagents. General method of
synthesis of organoboranes consists of the transmetallation
(N-Alkylanilino)dichloroboranes (5), prepared in situ from reaction of organometallic compounds with BX3.24 Boronic acid
N-alkylanilines and boron trichloride, are versatile interme- derivatives [RB(OH)2] are most conveniently synthesized by the
diates for the synthesis of ortho-functionalized aniline derivatives reaction of B(OR)3 with RLi or RMgX reagents, but boron
(eqs 3 5).15 The regioselective ortho hydroxyalkylation can be trihalides are more advantageous for transmetalation reactions
achieved with aromatic aldehydes.16 with less nucleophilic organometallic reagents based on Pb,25
Hg,26 Sn,27 and Zr28 (eqs 8 and 9).
NHMe
Ph4Sn + 2 BCl3 2 PhBCl2 + Ph2SnCl2 (8)
NHMe
1. ArCHO
BCl3, Et3N (3)
OH
benzene, " 2. H2O
(CH2)3Me
Ar (CH2)3Me
BCl3, CH2Cl2
Me
Cp2Zr (9)
N NHMe
0 °C rt
Cl
Cl2B
BCl2 1. ArCN, AlCl3
>90%
(4)
O
2. H2O
(5)
R
Redistribution or exchange reactions of R3B with boron tri-
R = alkyl, aryl
halides in the presence of catalytic amounts of hydride provides
an efficient synthesis of RBX2 and R2BX.29 Another convenient
NHMe
1. ArCN
and general method for the preparation of organodichloroboranes
(5)
2. AcOH, H2O involves treatment of alkyl, 1-alkenyl, and aryl boronates with
CHO
3. HCl, H2O
BCl3 in the presence of Iron(III) Chloride (3 mol %).30 Organo-
dichloroboranes are valuable synthetic reagents because of their
The reaction of (5) with alkyl and aryl nitriles and Aluminum
high Lewis acidity, and their utility is well demonstrated in the
Chloride catalyst provides ortho-acyl anilines.16 When chloroace-
syntheses of piperidine and pyrrolidine derivatives by the intra-
tonitrile is used, the products are ideal precursors for indole
molecular alkylation of azides (eq 10)31 or the synthesis of esters
synthesis.17 Use of isocyanides instead of nitriles provides ortho-
by the reaction with Ethyl Diazoacetate.32 The various organo-
formyl N-alkylanilines.18 Although these reactions with BCl3 are
borane derivatives, R3B, R2BCl, and RBCl2, all react with organic
restricted to N-alkylanilines, the use of Phenylboron Dichloride
allows the ortho-hydroxybenzylation of primary anilines.19
H
Analogously, boron trichloride induces ortho selective acyla-
1. HBCl2" SMe2
BCl3
Br N3 CH2Cl2
BCl3, pentane
tion of phenols at rt with nitriles, isocyanates, or acyl chlorides
(eq 6).20 The efficiency and regioselectivity of these reactions
2. H2O
B(OEt)2  78 °C rt
3. NaN3, EtOH, "
are best with BCl3 among the representative metal halides that
H
have been examined. In both the aniline and phenol substitutions
H
H
the boron atom acts as a template to bring the reactants together, N3
 N2 H2O
leading to cyclic intermediates and exclusively products of
(10)
40% KOH
N
ortho substitution. A similar ortho selective condensation of BCl2
H
H H
aromatic azides with BCl3 provides fused heterocycles containing
76%
nitrogen.21
A list of General Abbreviations appears on the front Endpapers
BORON TRICHLORIDE 3
O
azides and diazoacetates. However, especially facile reactions are
N
N
achieved by using organodichloroboranes (RBCl2). R3
O
BCl3
Dichloroborane and monochloroborane etherates or their
R3
Cl Cl
methyl sulfide complexes have been prepared by the reaction
CH2Cl2, -78 °C, R2 (14)
Cl
O HO
20 min
of borane and boron trichloride.33 However, hydroboration of
R2
alkenes with these borane reagents is usually very slow due R2 = H, R3 = H, 98%
to the slow dissociation of the complex. Dichloroborane pre-
R2 = H, R3 = Me, 95%
pared in pentane from boron trichloride and trimethylsilane shows
R2 = Me, R3 = H, 87%
unusually high reactivity with alkenes and alkynes; hydroboration
ć%
is instantaneous at -78 C (eq 11).34
OTr
BCl3
TBSO
OPMB
-30 °C
HSiMe3 Ä…-pinene
BCl3 HBCl2
BCl2 (11)
pentane
95% OH
 78 °C
TBSO
(15)
OPMB
Direct boronation of benzene derivatives with BCl3 in the
86%
presence of activated aluminum or AlCl3 provides arylboronic
acids after hydrolysis (eq 12).35 Chloroboration of acetylene with
boron trichloride produces dichloro(2-chloroethenyl)borane.36 Fully protected monosaccharides react with BCl3 in tetrahydro-
furan to effect a regioselective cleavage at the sites of primary
Similar reaction with phenylacetylene provides (E)-2-chloro-2-
alcohols, as illustrated for a D-mannose derivative in the course of
phenylethenylborane regio- and stereoselectively.37
an approach to L-gulose (eq 16).42
Al
PhH + BCl3 PhBCl2 (12)
I2 (trace), MeI (trace) TBS TBS
TBSO HO
150 °C
O O
BCl3
O O
60 79%
TBSO TBSO
(16)
THF
TBSO TBSO
OBn OBn
The syntheses of thioaldehydes, thioketones, thiolactones, and
81%
thiolactams from carbonyl compounds are readily achieved by
in situ preparation of B2S3 from bis(tricyclohexyltin) sulfide and
Boron trichloride alone does not remove isolated aryl methoxy
boron trichloride (eq 13).38 The high sulfurating ability of this
groups at low temperature, though it is extremely effective when
in situ prepared reagent can be attributed to its solubility in the
chelation is possible.43 However, the reactivity toward primary
reaction medium.
alkyl aryl ethers can be greatly enhanced in the presence of
n-Bu4NI (eq 17).44
toluene
B2S3 (13)
3 (Cy3Sn)=S + 2 BCl3
"
OR
OH
BCl3/n-Bu4NI
R1
R1
CH2Cl2, -78 to 0 °C, 2 h (17)
NH
S
R1 = Me, Et, Bn, -CH2OCH3, -CH2CH=CH2 64 98%
O S
S
S
94%, ", 7 h 92%, ", 3 h
unable to isolate
A mild and selective method for deprotection of tert-butyl aryl
sulfonamides has been developed. The reaction delivered good
yields ranging from 74 to 97%, without affecting bromides, nitro,
methoxy, and ketone carbonyl groups, for benzene and thiophene
derivatives of sulfonamides (eq 18).45
First Update
O O
O O
Yasunori Yamamoto & Norio Miyaura
S
BCl3
S
Hokkaido University, Sapporo, Japan N
NH2 (18)
R
H R
CH2Cl2, rt, 30 min
Cleavage of Ethers, Acetals, and Esters. Boron trichloride
74 97%
is a useful reagent for C O bond cleavage of ethers, acetals, and
esters in the presence of other sensitive functionality. Furo[3,4-c]
isoxazole undergoes regiospecific benzylic ether bond cleavage
without effecting the nonbenzylic C O bond or the isoxazole Condensation Reaction. BCl3 chlorinates aromatic aldehy-
ring when a methylene chloride solution is treated with equimolar des in refluxing hexane to produce aryl(dichloro)methanes, which
ć%
amount of boron trichloride at -78 C (eq 14).39,40 The benzylic also have been synthesized from aldehydes and PCl5. The reaction
C O bond cleavage provides a method for deprotection of trityl gives high yields for aromatic aldehydes, but it is not practical for
groups (eq 15).41 aliphatic aldehydes having enolizable protons (eq 19).46
Avoid Skin Contact with All Reagents
4 BORON TRICHLORIDE
i
Cl
Pr
Cl Cl
B i i
Cl Pr Pr
O
CHO i
BCl3 N Pr
BCl3
(22)
N N
R1
Cl
hexane
hexane B
i
R1
Pr N
Cl
i i
Pr Pr
Pri
Cl
39%
(19)
Cl
R1
The geminal acylation of acetals and ketones with 1,2-silylated
enediols is a method for the introduction of a 1,3-cyclopentane-
76 99%
dione moiety to carbonyl compounds. BF3·OEt2 results in low
yields in aldol reactions of silylated endiol and ketones, but BCl3
R1 = H, p-Cl, o-Cl, p-Br, m-Br, p-NO2, m-NO2, p-Me
mediates the reaction in high yields (eq 23).50
Cl
Reaction of aromatic aldehydes, BCl3, and styrene containing a
TMSO OTMS
ć% B
radical inhibitor at 0 C in dichloromethane yields diastereomeric
O
O
O
1. H2O
mixtures of 1,3-diaryl-1,3-dichloropropanes. A carbocation inter-
t
t
Bu
Bu
mediate has been postulated. Isolated yields are 80 99% when
BCl3, CH2Cl2
2. TFA
O
two substituents are electron-withdrawing groups, but donating -78 °C
substituents may lower the yields to 57 85% due to instability of
the benzyl chlorides toward chromatography (eq 20).47
O
t (23)
Bu
CHO
BCl3
O
+
R2
R1
CH2Cl2
98%
Cl Cl
Anilinodichloroboranes can be prepared in situ from anilines
(20)
R1 R2 and boron trichloride, as intermediates for the regiospecific syn-
thesis of ortho-acyl anilines, via condensation with nitriles. The
reaction has been carried out with BCl3 and AlCl3, but a combina-
57 99%
tion of BCl3 and GaCl3 affords high yields without accompanying
R1 = H, p-F, p-Cl, p-Me, p-CN, p-NO2, o-Br, o-F
ring-opened products of cyclopropanenitrile (eq 24).51
R2 = H, p-F, p-Me
+
C
Cl
Cl
Analogously, the reaction of boron trichloride with aromatic CN
H3O+
N
aldehydes and 2 equiv of an arylacetylene yields predominantly
BCl3, GaCl3
BCl2
(E,Z)-dienes in good yields (eq 21).48 The proposed mechanism NH2 PhCl, 100 °C
N
H2
involves addition of BCl3 to the alkyne followed by Grignard-type
20 h
addition of the resulting 1-alkenylboron intermediate to aldehyde.
Addition of BCl3 to imine C=N double bonds has demonstrated
in the synthesis of 1,3,2-diazaborolidine, via reaction between
BCl3 and 1,4-diazadiene in hexane (eq 22).49
Cl
O (24)
NH2
BCl3
74%
Ar1CHO
+ 2 Ar2
CH2Cl2
Cl Ar1 Ar2
Organothiophenes are synthesized from 1,4-butanediones by
(21)
boron trichloride-mediated sulfuration of carbonyl compounds
Ar2 Cl
with hexamethyldisilathiane at room temperature (eq 25).52c
62 76% BCl3 mediates analogous sulfuration of ketones and diketones
with bis(trimethylsilyl)sulfide, bis(tricyclohexyltin)sulfide, bis
Ar1 = Ph, 4-BrC6H4, 4-FC6H4, 4-NCC6H4, 4-MeC6H4
(tri-n-butyltin)sulfide, and bis(triphenyltin)sulfide in high
Ar2 = Ph, 4-FC6H4, 4-MeC6H4
yields.52a,b
A list of General Abbreviations appears on the front Endpapers
BORON TRICHLORIDE 5
H21C10
BCl2
BCl3, (Me3Si)2S
BCl3
Br
toluene, rt
Me3SiH
S S Me3SiH
O O
H21C10
Cl
(25)
B
[O]
(29)
Br
HO
S S S
H
H
51%
95%, 57% ee
Hydroboration of chloroalkynes with HBCl2 gives É-halogeno-
Aromatic hydroxy aldehydes can be prepared by the action of
alkyldichloroboranes for the synthesis of trans-pyrrolidines or
BCl3 on aryl formates via Fries rearangement (eq 26).53 The yields
piperidines via a sequence of a Diels-Alder reaction and amina-
of the aldehydes are lowered by subsequent condensation reac-
tion with benzyl azide (eq 30).57 Both the Diels-Alder reaction and
tions.
amination reaction take place smoothly when Lewis acidic boron
reagents such as alkyldichloroboranes are used. trans-Cyclo-
HO CHO
OCHO
alkanopiperidines and cycloalkanopyrrolidines have also been
BCl3 synthesized via analogous hydroboration-intramolecular cycliza-
tion sequences.58
1,2-dichloroethane
(26)
20 35 °C
Cl
BCl3
98%
Cl
Et3SiH
Cl2B
Reduction. When BCl3 is used as the chelating agent in the
Cl 1. BnN3/MeOH
(30)
reduction of ²-hydroxy ketones, ketones are reduced with high
2. NaOH
BCl2
diastereoselctivity to give syn-1,3-diols (eq 27).54 The avoidance N
of a 1,3-diaxal-like interaction appears responsible for the high
Bn
49%
diastereoselectivity.
Transmetallation of organolithium, -magnesium, -silicon, or
-tin compounds with BCl3 is another reliable method in the
O OH OH OH
1. BCl3, -78 °C
synthesis of organoboron compounds. The reaction of organo-
(27)
2. Me3N·BH3, -78 °C
Ph R Ph R
lithium reagents with BCl3 suffers from the formation of
gummy residues of lithium tetraalkylborates. In contrast, tris(3,3-
yield 77 96%
dimethyl-1-butynyl)borane is obtained quantitatively when the re-
syn 92 95%
ć%
action is conducted at -78 C in pentane (eq 31).59
BCl3
3 n-BuLi
(31)
B
98%
3
Synthesis of Organoboron Reagents. A number of methods
for the synthesis of chloro(organo)boranes are well established.
Transmetallation between a zirconacycle and 1 equiv boron
A general method involves hydroboration of alkynes and alkenes
trichloride is used for the synthesis of 1-chloro-trans-2,5-
with dichloroboranes or transmetallation of Li, Mg, Si, Sn, and Zr
diphenylborolane with retention of stereochemistry (eq 32).60
compounds to boron trichloride.
Trialkylsilanes or dialkylsilanes react rapidly with boron
Ph
trichloride in the absence of ethereal solvents or other nucleophiles
Cp2ZrCl2 BCl3
to form unsolvated dichloroboranes which have been synthesized 2 Cp2Zr
Ph
t-BuLi
as diethyl ether or dimethylsulfide complexes. Hydroboration of
Ph
alkynes with these free dichloroboranes produces uncomplexed
alkenyl(dichloro)boranes (eq 28).55 The protocol provides a
Ph
OH
method for the preparation of IpcBHCl for asymmetric hydro-
NaBO3
boration (eq 29).56 Ph
(32)
Cl B
Ph
OH
Ph
BCl2
Me3SiH
Me3SiH n-Bu
85% 60%
BCl2
(28)
n-Bu
n-Bu
BCl2
BCl3 BCl3
Organotin compounds readily react with BCl3 to give alkyl- or
84%
aryl(dichloro)boranes. Transmetallation between vinylstannnane
Avoid Skin Contact with All Reagents
6 BORON TRICHLORIDE
ć%
and BCl3 at -78 C affords thermally unstable vinyldichlorobo- Ar2
Ar2 N
rane, which is directly used for next the reaction without isola-
1. BCl3 Ar1 (38)
O
B
Ar1
tion (eq 33).61 Reaction of a stannacycle with BCl3 affords the
Si 2. pinacol, Et3N
Et O
B-chloroboracycle (eq 34).62
Me2
Et
A1 = Ph, 3-ClC6H4 65 82%
A2 = Ph, 4-MeOC6H4, 4-Me2N(CH2)2OC6H4,
BCl3 HNiPr2 BCl
BCl2
SnBu3
4-CF3C6H4, 4-EtO2CC6H4, 4- ClC6H4, 4-MeC6H4
NiPr2 (33)
83%
Related Reagents. Bis(tricyclohexyltin) Sulfide Boron
Trichloride.
t
t
Bu
Bu
N
N 1. Gerrard, W.; Lappert, M. F., Chem. Rev. 1958, 58, 1081.
BCl3
(34)
BCl
SnBu2
2. (a) Bhatt, M. V.; Kulkarni, S. U., Synthesis 1983, 249. (b) Greene, T. W.,
CH2Cl2, -65 °C to rt
Protective Groups in Organic Synthesis; Wiley: New York, 1981.
49%
3. (a) Gerrard, W.; Lappert, M. F.; Silver, H. B., Proc. Chem. Soc. 1957,
19. (b) Borgulya, J.; Madeja, R.; Fahrni, P.; Hansen, H.-J.; Schmid, H.;
Barner, R., Helv. Chim. Acta 1973, 56, 14.
Reaction of 1,8-bis(trimethylstannyl)naphthalene with an
4. (a) Dean, R. B.; Goodchild, J.; Houghton, L. E.; Martin, J. A.,
ć% ć%
excess of BCl3 at -78 C is followed by warming to 0 C Tetrahedron Lett. 1966, 4153. (b) Arkley, V.; Attenburrow, J.; Gregory, G.
I.; Walker, T., J. Chem. Soc. 1962, 1260. (c) Barton, D. H. R.; Bould, L.;
results in the synthesis of a Lewis acid possessing a boryl and
Clive, D. L. J.; Magnus, P. D.; Hase, T., J. Chem. Soc. (C) 1971, 2204. (d)
a stannyl moiety at the peri-positions of the naphthalene core.
Carvalho, C. F.; Seargent, M. V., J. Chem. Soc., Chem. Commun. 1984,
ć%
At 50 C, chloride-methyl exchange occurs via intramolecular
227.
transmetallation (eq 35).63
5. (a) Teitel, S.; O Brien, J.; Brossi, A., J. Org. Chem. 1972, 37, 3368.
(b) Teitel, S.; O Brien, J. P., J. Org. Chem. 1976, 41, 1657.
MeClB SnMeCl2 6. Gero, S. D., Tetrahedron Lett. 1966, 591.
Me3Sn SnMe3 Cl2B SnMe2Cl
7. Perdomo, G. R.; Krepinsky, J. J., Tetrahedron Lett. 1987, 28, 5595.
BCl3
50 °C
8. Williard, P. G.; Fryhle, C. B., Tetrahedron Lett. 1980, 21, 3731.
(35)
CH2Cl2
9. Manchand, P. S., J. Chem. Soc., Chem. Commun. 1971, 667.
-78 to 0 °C
10. Yazawa, H.; Nakamura, H.; Tanaka, K.; Kariyone, K., Tetrahedron Lett.
84%
96%
1974, 3991.
11. Hansen, K. C.; Solleder, G. B.; Holland, C. L., J. Org. Chem. 1974, 39,
267.
Although silicon is not as easily displaced as tin derivatives,
12. Chow, H.-F.; Seebach, D., Helv. Chim. Acta 1986, 69, 604.
aryl- and alkenylsilanes react with boron trichloride.64a,b Dichloro
13. Sugasawa, T.; Toyoda, T.; Sasakura, K., Synth. Commun. 1979, 9, 515.
(4-methyl-furan-3-yl)borane (eq 36)64c and 1,1-bis(trichloro-
14. Sugasawa, T.; Toyoda, T.; Tetrahedron Lett. 1979, 1423.
boryl)ferrocene (eq 37)65a are easily available by treating silicon
15. Sugasawa, T., J. Synth. Org. Chem. Jpn. 1981, 39, 39.
compounds with an excess of boron trichloride in dichloro-
16. Sugasawa, T.; Toyoda, T.; Adachi, M.; Sasakura, K., J. Am. Chem. Soc.
methane.
1978, 100, 4842.
17. Sugasawa, T.; Adachi, M.; Sasakura, K.; Kitagawa, A., J. Org. Chem.
BCl2
SiMe3 1979, 44, 578.
BCl3
(36) 18. Sugasawa, T.; Hamana, H.; Toyoda, T.; Adachi, M., Synthesis 1979, 99.
CH2Cl2, -78 to 0 °C
19. Toyoda, T.; Sasakura, K.; Sugasawa, T., Tetrahedron Lett. 1980, 21, 173.
O
O
20. (a) Toyoda, T.; Sasakura, K.; Sugasawa, T., J. Org. Chem. 1981, 46,
90%
189. (b) Piccolo, O.; Filippini, L.; Tinucci, L.; Valoti, E.; Citterio, A.,
Tetrahedron 1986, 42, 885.
21. (a) Zanirato, P., J. Chem. Soc., Chem. Commun. 1983, 1065. (b)
SiMe3 BCl2
BCl3
Spagnolo, P.; Zanirato, P., J. Chem. Soc., Perkin Trans. 1 1988, 2615.
(37)
Fe Fe
CH2Cl2
22. Paetzold, P. I.; Kosma, S., Chem. Ber. 1970, 103, 2003.
SiMe3 BCl2
23. Helfert, H.; Fahr, E., Angew. Chem., Int. Ed. Engl. 1970, 9, 372.
98% 24. (a) Nesmeyanov, A. N.; Kocheshkov, K. A. Methods of Elemento-
Organic Chemistry; North-Holland: Amsterdam, 1967; 1, p 20. (b)
Mikhailov, B. M.; Bubnov, Y. N. Organoboron Compounds in Organic
The stereoselective transmetallation of 1-alkenylsilanes to BCl3
Synthesis; Harwood: Amsterdam, 1984.
ć%
in CH2Cl2 at -41 C occurs with retention of stereochemistry
25. Holliday, A. K.; Jessop, G. N., J. Chem. Soc. (A) 1967, 889.
(eq 38).66 Subsequent treatment with pinacol affords pinacol
26. Gerrard, W.; Howarth, M.; Mooney, E. F.; Pratt, D. E., J. Chem. Soc.
1-alkenylboronates which undergo palladium-catalyzed cross- 1963, 1582.
coupling with aromatic halides to provide stereodefined tetra(aryl)
27. (a) Niedenzu, K.; Dawson, J. W., J. Am. Chem. Soc. 1960, 82, 4223.
ethenes. (b) Brinkman, F. E.; Stone, F. G. A., Chem. Ind. (London) 1959, 254.
A list of General Abbreviations appears on the front Endpapers
BORON TRICHLORIDE 7
28. Cole, T. E.; Quintanilla, R.; Rodewald, S., Organometallics 1991, 10, 47. Kabalka, G. W.; Wu, Z.; Ju, Y., Tetrahedron Lett. 2001, 42, 5793.
3777.
48. Kabalka, G. W.; Wu, Z.; Ju, Y., Org. Lett. 2002, 4, 1491.
29. Brown, H. C.; Levy, A. B., J. Organomet. Chem. 1972, 44, 233.
49. Mair, F. S.; Manning, R.; Pritchard, R. G.; Warren, J. E., Chem. Commun.
30. (a) Brindley, P. B.; Gerrard, W.; Lappert, M. F., J. Chem. Soc. 1956, 824. 2001, 1136.
(b) Brown, H. C.; Salunkhe, A. M.; Argade, A. B., Organometallics
50. Crane, S. N.; Burnell, D. J., J. Org. Chem. 1998, 63, 5708.
1992, 11, 3094.
51. Houpis, I. N.; Molina, A.; Douglas, A. W.; Xavier, L.; Lynch, J.; Volante,
31. (a) Jego, J. M.; Carboni, B.; Vaultier, M.; Carrie , R., J. Chem. Soc.,
P. R.; Reider, P. J., Tetrahedron Lett. 1994, 35, 6811.
Chem. Commun. 1989, 142. (b) Brown, H. C.; Salunkhe, A. M.,
52. (a) Steliou, K.; Mrani, M., J. Am. Chem. Soc. 1982, 104, 3104.
Tetrahedron Lett. 1993, 34, 1265.
(b) Freeman, F.; Kim, D. S. H. L.; Rodriguez, E., J. Org. Chem. 1992,
32. Hooz, J.; Bridson, J. N.; Calzada, J. G.; Brown, H. C.; Midland, M. M.;
57, 1722. (c) Von Kieserizky, F.; Hellberg, J.; Wang, X.; Inganäs, O.,
Levy, A. B., J. Org. Chem. 1973, 38, 2574.
Synthesis 2002, 1195.
33. (a) Brown, H. C., Organic Syntheses via Boranes; Wiley: New York,
53. Ziegler, G.; Haug, E.; Frey, W.; Kantlehner, W., Z. Naturforsh 2001, 56b,
1975; p 45. (b) Brown, H. C.; Kulkarni, S. U., J. Organomet. Chem.
1178.
1982, 239, 23. (c) Brown, H. C.; Ravindran, N., Inorg. Chem. 1977, 16,
54. Sarko, C. R.; Collibee, S. E.; Knorr, A. L.; DiMare, M., J. Org. Chem.
2938.
1996, 61, 868.
34. Soundararajan, R.; Matteson, D. S., J. Org. Chem. 1990, 55, 2274.
55. Soundararajan, R.; Matteson, D. S., Organometallics 1995, 14, 4157.
35. (a) Muetterties, E. L., J. Am. Chem. Soc. 1960, 82, 4163. (b) Lengyel,
56. Dhokte, U. P.; Kulkarni, S. V.; Brown, H. C., J. Org. Chem. 1996, 61,
B.; Csakvari, B., Z. Anorg. Allg. Chem. 1963, 322, 103.
5140.
36. Lappert, M. F.; Prokai, B., J. Organomet. Chem. 1964, 1, 384.
57. Jego, J.-M.; Carboni, B.; Youssofi, A.; Vaultier, M., Synlett 1993, 595.
37. Blackborow, J. R., J. Chem. Soc., Perkin Trans. 2 1973, 1989.
58. Brown, H. C.; Salunkhe, A. M., Tetrahedron Lett. 1993, 34, 1265.
38. Steliou, K.; Mrani, M., J. Am. Chem. Soc. 1982, 104, 3104.
59. Bayer, M. J.; Pritzkow, H.; Siebert, W., Eur. J. Inorg. Chem. 2002, 2069.
39. Kim, H. J.; Lee, J. H.; Olmstead, M. M.; Kurth, M. J., J. Org. Chem.
60. Cole, T. E.; Gonzáles, T., Tetrahedron Lett. 1997, 38, 8487.
1992, 57, 6513.
61. Ashe, A. J., III; Fang, X.; Kampf, J. W., Organometallics 2000, 19, 4935.
40. Kim, H. J.; Lee, Y. J., Synth. Commun. 1998, 28, 3527.
62. Liu, S.-Y.; Lo, M. M.-C.; Fu, G. C., Angew. Chem., Int. Ed. 2002, 41,
41. Jones, G. B.; Hynd, G.; Wright, J. M.; Sharma, A., J. Org. Chem. 2000,
174.
65, 263.
63. Schulte, M.; Gabbaï, F. P., Can. J. Chem. 2002, 80, 1308.
42. Yang, Y.-Y.; Yang, W.-B.; Teo, C.-F.; Lin, C.-H., Synlett 2000, 1634.
64. (a) Farinola, G. M.; Fiandanese, V.; Mazzone, L.; Naso, F., J. Chem.
43. (a) Covarrubias-Zśńiga, A.; Gonzalez-Lucas, A.; Domínguez, M. M.,
Soc., Chem. Commun. 1995, 2523. (b) Babudri, F.; Farinola, G. M.;
Tetrahedron 2003, 59, 1989. (b) Covarrubias-Zśńiga, A.; Gonzalez-
Fiandanese, V.; Mazzone, L.; Naso, F., Tetrahedron 1998, 54, 1085.
Lucas, A., Tetrahedron Lett. 1998, 39, 2881.
(c) Yick, C.-Y.; Wong, H. N. C., Tetrahedron 2001, 57, 6935.
44. Brooks, P. R.; Wirtz, M. C.; Vetelino, M. G.; Rescek, D. M.; Woodworth,
65. (a) Deck, P. A.; Fisher, T. S.; Downey, J. S., Organometallics 1997, 16,
G. F.; Morgan, B, P.; Coe, J. W., J. Org. Chem. 1999, 64, 9719.
1193. (b) Jäkle, F.; Berenbaum, A.; Lough, A. J.; Manners, I., Chem. Eur.
45. Wan, Y.; Wu, X.; Kannan, M. A.; Alterman, M., Tetrahedron Lett. 2003,
J. 2000, 6 2762. (c) Wrackmeyer, B.; Ayazi, A.; Milius, W.; Herberhold,
44, 4523.
M., J. Organomet. Chem. 2003, 682, 180.
46. Kabalka, G. W.; Wu, Z., Tetrahedron Lett. 2000, 41, 579.
66. Itami, K.; Kamei, T.; Yoshida, J.-I., J. Am. Chem. Soc. 2003, 125, 14670.
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