ALUMINUM

1

Aluminum

1

Al

[7429-90-5]

Al

(MW 26.98)

InChI = 1/Al
InChIKey = XAGFODPZIPBFFR-UHFFFAOYAX

(reducing agent for many functional groups;

1

can aluminate

double bonds

2

or insert into carbon–halogen bonds; promotes

propargylation of carbonyl compounds; in combination with
metallic Sn or PbBr

2

mediates Barbier-type allylation of carbonyl

compounds or imines)

Physical Data:

mp 660.37

◦

C; bp 2467

◦

C; d 2.702 g cm

−

3

;

E

◦

(aq) Al

3+

/Al

0

= −1.66 V.

Solubility:

reacts with dil HCl, H

2

SO

4

, KOH, and NaOH, hot

AcOH; insol conc HNO

3

.

Form Supplied in:

silver-white, malleable, ductile metal; widely

available in foil, granules, ingot, pellets, powder, rod, shot, wire.

Handling, Storage, and Precautions:

Al foil is moisture sensi-

tive, powder is moisture sensitive and flammable. Aluminum is
reputed to be practically nontoxic.

Functional Group Reductions.

Aluminum will reduce

ketones or aldehydes to alcohols or saturated hydrocarbons, ni-
tro compounds and Shiff bases to amines, and alkyl halides to
alkanes. Aluminum also effects reductive dimerization of ketones
and dehalogenation of polyhalogenated compounds. In combina-
tion with Nickel(II) Chloride hexahydrate in THF, metallic Al will
reduce acyl chlorides, anhydrides and nitriles, epoxides, and disul-
fides. Moreover, aluminum exhibits pronounced chemoselectivity
in reduction of polyfunctionalized compounds.

3

Aromatic ketones are especially readily reduced by aluminum.

Reduction of 2-methyl-2-phenyl-1-indanone with Al in i-PrOH
proceeds with diastereoselectivity (trans/cis ratio in alcohol
formed is 90:10) better than that observed with Li, Na, or K.

4

Quinone (1) is reduced with Al in 85% H

2

SO

4

to the 6,13-dihydro

product (2) (eq 1) while the 6-hydroxy derivative is formed in
reaction of (1) with Cu in 96% H

2

SO

4

.

5

N

H

H

N

O

O

O

O

N

H

H

N

O

O

(1)

Al–85% H

2

SO

4

80 °C

82%

(1)

(2)

Reductive dimerization of tetralone to 3,3

′

,4,4

′

-tetrahydro-

1,1

′

-binaphthyl is mediated by Al foil activated with Mercury

(II) Chloride.

6

A facile reduction of aromatic ketones and alde-

hydes into corresponding alcohols is readily achieved employing
Al powder in combination with NiCl

2

·

6H

2

O in THF.

3

Reduction of (thiazolyl)(acylaminomethyl)ketones with the

reagent prepared from Al dissolved in i-PrOH in the pres-
ence of Aluminum Chloride,

7a

and oxidation of aluminum tris

(3-pentanoxide-1,2-d

5

) (from the alcohol, Al shot, and a trace of

HgCl

2

) with benzophenone,

7b

can be considered special cases of

modified Meerwein–Ponndorf–Verley and Oppenauer reactions.

Aromatic nitro compounds are reduced to anilines with Al

powder in AcOH–HCl

8

or with Al–NiCl

2

·

6H

2

O.

3

Reactions

of nitrobenzene with Al turnings (heating in aq H

2

SO

4

)

9a

or

Al–Fe alloy (in 50% NaOH)

9b

afford p-aminophenol and N,N

′

-

diphenylhydrazine, respectively.

Al foil activated with HgCl

2

and Hg is capable of reducing

both aliphatic

10b

and aromatic Shiff bases

10b

to secondary amines.

For aromatic substrates, the process is substantially complicated
by reductive dimerization of the azomethines. It is this particular
reagent (not other metals such as Na, Mg, or Zn) that causes un-
usual ring contractions of lumazines

11a

and pterines

11b

to theo-

phyllines (eq 2) and guanines respectively, via a radical anion
formed upon C=N double bond reduction.

N

N

N

N

O

O

OEt

Me

Me

N

N

N

N

O

O

OEt

Me

Me

N

N

N

H

N

Me

Me

O

O

Al(HgCl

2

)

aq MeOH–NH

3

81%

–

•

(2)

1,2-Dehalogenation occurs when polyhalogenated substrates

react with Al turnings in the presence of AlCl

3

.

12

For alicyclic

compounds it is a stereospecific process (eq 3).

12b

Br

Cl

Br

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Br

Cl

Cl

Cl

Cl

Cl

Cl

Br

Cl

Cl

Br

Cl

Cl

Cl

Cl

Al turnings, dry ether

reflux, 3 h

97%

Al

Al turnings, dry ether

reflux, 3 h

73%

(3)

When 2–5% NaOH is added, Al (powder or turnings) reduces

1,1-dibromocyclopropanes or 7,7-dibromonorcaranes into mono-
bromides with modest cis or exo stereoselectivity.

13

A small

amount

of

Al

powder

promotes

halide

exchange

and

3-chlorophthalide

is

converted

almost

quantitatively

into

3-bromophthalide in a reaction with dry HBr.

14

On refluxing with an excess of an alkyl or aryl halide, Al inserts

into the carbon–halogen bond.

15

Primarily a mixture of sesqui-

halides 3 is formed (eq 4).

15

With alkyl halides,

16

the sesquihalide

Avoid Skin Contact with All Reagents

2

ALUMINUM

mixture formed in situ can be easily reduced to produce trialky-
laluminum compounds (eq 5).

16c

In case of aryl halides, (3) is an

excellent reagent for transfer of an aryl moiety from Al to other
elements (P, Sn) (eq 6).

17

Mixture (3) also reacts with organic

halides to form organoaluminum compounds. However, a more
versatile method of synthesis involves the reductive replacement
of Hg from organomercury compounds with Al (eq 7).

18

RX

+

Al

R

2

AlX

+

RAlX

2

(4)

(3)

X = Cl, Br, I

2 Al

+

3 Mg

+

6 BuI

+

2 PhOEt

octane

90–105 °C

80%

2 AlBu

3

·

PhOEt

+

3 MgI

2

(5)

(6)

Ph

3

Al

2

Cl

3

+

PCl

3

PhCl, rt →180–200 °C, 2 h

91%

Ph

3

P

+

2 AlCl

3

(7)

3 [H

2

C=CH(CH

2

)

2

]Hg

+

2 Al

sealed tube

rt, 2 weeks

100%

2 [H

2

C=CH(CH

2

)

2

CH

2

]

3

Al

+

3 Hg

Reduction of element–halogen bonds by Al or Al-promoted

cleavage of other bonds is widely used in synthesis of organo-
boron,

19

organosilicon,

20

organogermanium,

21

and organophos-

phorus compounds,

22

as well as π-complexes of titanium,

23

vanadium,

23b

and zirconium.

24

Al powder in combination with

AlCl

3

and Iodine (or Iodo(iodomethyl)mercury) induces boryla-

tion of C

6

H

6

with Boron Trichloride to form PhBCl

2

.

19a

Mix-

tures of amines and triarylborates are reduced to borazanes by
aluminum–iodine.

19b

On electrochemical reduction with a sacri-

ficial Al anode, chlorosilanes undergo dimerization

20a

or cross-

coupling if two different chlorosilanes react.

20b

Tetraalkylger-

manes are cleaved by the system Al–I

2

to yield iodogermanes.

21

A mild and neutral reducing system of Al–NiCl

2

·

6H

2

O–THF

reduces enones to saturated aldehydes (eq 8),

3

nitriles to amines,

acid chlorides and anhydrides to aldehydes, disulfides to thiols,
and epoxides to the alcohols. Isolated double bonds, carboxy-
lic acids, esters, lactones, primary, benzyl and allyl halides,
aliphatic aldehydes and ketones as well as aliphatic nitro
compounds are inert to this agent.

3

(8)

CHO

CHO

Al–NiCl

2

, THF

10 min

80%

In combination with Antimony(III) Chloride, metallic Al

smoothly reduces both aliphatic and aromatic aldehydes to alco-
hols (yield 50–98%). Reduction proceeds chemoselectively and
PhCHO is preferably reduced in competition with PhCOMe. Un-
like Al–NiCl

2

, reduction of α,β-unsaturated aldehydes with this

system occurs only at the C=O group, leaving C=C double bonds
intact.

25

Reactions of Aluminum Alkoxides and Phenoxides.

A

facile method of alcohol dehydration is based on thermal decom-
position of the derived Al alkoxide which, depending on the al-
cohol structure, commences in the range of 200–270

◦

C.

26

Al foil

(HgCl

2

-activated) in i-PrOH promotes deoxygenation of epox-

ides, giving the corresponding alkenes.

27

Friedel–Crafts Alkylation Catalyst.

Aluminum catalyzes

ortho

-alkylation of anilines and phenols with alkenes.

28,29

Pre-

formed aluminum anilides or phenoxides exhibit high suscepti-
bility toward alkene attack and usually o,o

′

-dialkylated products

predominate.

29a,b

Selective ortho-alkylation of phenol can be ac-

complished using aluminum soft drink cans as the reagent (eq 9).

28

OH

OH Ph

(9)

1. 0.15–1.0% Al, 140 °C

2. PhCH=CH

2

80%

Alumination Agent. A facile hydroalumination of carbon–

carbon double bonds yielding trialkylaluminum compounds takes
place in a three-component mixture consisting of an alkene, hy-
drogen, and Al (eq 10).

2

The process involves intermediate for-

mation of a dialkylaluminum hydride which adds to the third
alkene molecule, affording the trialkylaluminum. To elucidate the
mechanism of the reaction, direct synthesis of organoaluminum
compounds in the condensed phase from Al vapor and alkene is
of noticeable importance.

30

(10)

2 Al

+

3 H

2

+

3 H

2

C=CMe

2

2 (Me

2

CHCH

2

)

3

Al

Selective Propargylation. The problem of propargyl group

introduction in various substrates without propargyl–allenyl rear-
rangement has been addressed using alumination (Al in the pres-
ence of HgCl

2

) of propargylic bromides followed by addition of

a carbonyl substrate to the organoaluminum reagent formed in
situ.

31

This approach has been used to prepare propargylic alco-

hols from ketones

32a

and aldehydes,

32b

propargylic ethers from

α

-chloro ethers

33a

and acetals,

33b

acetals of propargylic carbalde-

hydes from orthoformates (eq 11),

34

homopropargylic ethers and

sulfides from chloromethyl ethers and sulfides.

35

Propargylic

compounds prepared in this manner have been used in the syn-
thesis of spirilloxanthin, 3,4-dehydro-rhodopin,

32a

ecdysteroid

analogs,

35

and lycorine precursors.

36

Br

PrO

OPr

(11)

1. Al, ether

2. HC(OPr)

3

, –80 °C

82%

Aluminum is presumably a unique partner for condensations

of this type because, for example, Zn always gives a mixture of
alkynic and allenic alcohols.

31,32a

Aluminum–Tin(0) and Aluminum–Tin(II) Systems.

A

strong impetus for current applications of Al in organic synthesis
has resulted from a study on allylation of carbonyl compounds
mediated by the combination of stoichiometric amounts of metal-
lic Al and Tin, and the observation of extensive acceleration in
the presence of water.

37

Typical procedures suggest that a car-

bonyl compound, allylic bromide, Al, and Sn should be used in
a ratio 1:1.2–2:1:1. Allylation with unsymmetrically substituted
allylic halides proceeds with complete rearrangement in the al-
lylic unit and shows considerable diastereoselectivity (eq 12).

37a

A list of General Abbreviations appears on the front Endpapers

ALUMINUM

3

Intramolecular versions of the reaction have been used in synthe-
ses of five- and six-membered cyclic alcohols.

37c

CHO

Br

HO

(12)

Al–Sn (1:1)

THF–H

2

O (2:0.2), 2 h

81%

+

erythro

:threo = 78:22

A combination of Al powder (2 equiv) and Tin(II) Chloride

(0.1 equiv) in an organic solvent is even more active than the Al–Sn
couple and addition of water to the solvent enhances the allylation
rate remarkably.

38

Carbonyl compounds are almost inert to ally-

lation if 1 equiv of Al and only 0.1 equiv of Sn is used,

38

whereas

metallic Sn or SnCl

2

in aprotic solvents convert allylic halides to

allylstannanes in situ, which readily allylate carbonyl substrates

39

with complete rearrangement in the entering allylic unit.

39a

It has

been established that Al effects both oxidative addition of metallic
Sn to allyl halide and reductive regeneration of Sn

0

from Sn

II

and

Sn

IV

for a recycle use.

38

Thus all allylation reactions in Al–Sn

or Al–Sn

II

systems can be considered as aluminum-promoted and

tin-recycled processes.

Al–Sn mediated condensation of aldehydes with α-(bromo-

methyl)acrylates

40

represents a facile synthesis of α-methylene-

γ

-butyrolactones (eq 13).

40a

This procedure is more efficient than

allylations promoted by Cr

II

(see Chromium(II) Chloride and

Lithium Aluminum Hydride).

40b

CO

2

Et

Br

O

C

5

H

11

O

(13)

1. Al–Sn, Et

2

O–H

2

O, reflux, 12 h

2. TsOH
51%

+

C

5

H

11

CHO

Almost exclusive threo diastereoselectivity is characteristic of

the reactions of cinnamyl chloride with aldehydes promoted by
Al–Sn

41a

or Al–SnCl

2

.

41b

Aldehydes containing a chiral center

adjacent to the C=O group afford threo Cram and threo anti-
Cram products with the former predominating (eq 14) in contrast
to magnesium-mediated reactions of the same partners, which give
all four possible diastereomers.

41a

O

H

t

-Bu

Ph

Cl

t

-Bu

t

-Bu

Ph

Ph

OH

OH

(14)

+

Sn–Al, Et

2

O–H

2

O

rt, 24 h

>90%

+

>9:1

Unlike other allylation processes mediated by Al–Sn, no iso-

merization of the allylic unit is observed in the reaction of aromatic
aldehydes with CH

2

=

CHCF

2

Cl in the presence of Al–10% SnCl

2

in EtOH–AcOH–H

2

O. This reaction regiospecifically leads to 1-

aryl-2,2-difluoro-3-buten-1-ols.

42

Aluminum–Lead Bromide. Three main processes, Barbier-

type allylations, reductive coupling of carbonyls, and addition of
polyhaloalkanes to carbonyls are mediated by this system which
has been extensively studied in the past decade. PbBr

2

is used in

a catalytic amount (molar ratio Al foil:PbBr

2

= 100:1–5), of great

importance because of the hazardous properties of lead.

Al–PbBr

2

promoted allylation of various carbonyl compounds

can be performed at ambient temperature in DMF, aqueous THF,
or aqueous MeOH while nonaqueous THF, MeOH, and MeCN
are not suitable. A moderate excess of allylic bromide (10–100%
relative to carbonyl substrate) is recommended. Under these
conditions the addition to α,β-enones proceeds regiospecifically
in a 1,2-fashion (eq 15).

43

Ph

O

Br

Ph

OH

+

Al–PbBr

2

(1.1:0.03), DMF, rt, 2 h, 96%

(15)

Pb

II

Pb

0

Al

III

Al

0

Metallic Al itself does not promote allylation which is, how-

ever, mediated by Pb–Bu

4

NBr.

44

The observed stoichiometry

(carbonyl substrate:CH

2

=

CHCH

2

Br:Pb = 1:1:1) suggests that

the reaction involves an active organolead(II) rather than orga-
nolead(IV) reagent, in contrast to the tin promoted reactions.

38,39

The in situ generated Pb

0

is much more effective than commer-

cially available Pb and turnover of the Pb

0

catalyst in the range

14–77 is attained.

43

This type of Barbier-type allylation has been applied to C-3

chain elongation of cephalosporins.

45

Acetals RCH(OMe)

2

(4) as masked carbonyl compounds also

undergo Barbier-type allylation mediated by Al–PbBr

2

–AlBr

3

(molar ratio 1:0.03:0.1) to form homoallylic ethers (5).

46

The

presence of Aluminum Bromide is critical because no allylation
product is formed in the absence of this co-catalyst. Reaction path-
ways depend strongly on quantities of reactants and reagents, es-
pecially in the case of acetals of aromatic aldehydes. An increase
of AlBr

3

from 0.1 to 0.5 equiv is accompanied by reductive ho-

mocoupling to 1,2-diaryl-1,2-dimethoxyethanes (6) If the ratio
CH

2

=

CHCH

2

Br to (4) is higher than 2:1, commonly used in such

processes, diallylation and reductive homocoupling of monoally-
lated products effectively compete with monoallylation. The re-
sults reveal formation of cations (7) in the presence of AlBr

3

as an

acid catalyst. The cations are either further allylated or reduced
by Pb

0

to furnish dimers (6) (eq 16).

46

Replacement of AlBr

3

with Trifluoroacetic Acid (TFA) (1 equiv) causes a complete shift
of the reaction toward formation of homocoupling products (6)
from arene and heteroaromatic carbaldehyde acetals.

47

To pro-

mote homocoupling, although less efficiently, VCl

3

or Cobalt(II)

Chloride or Tin(II) Bromide can be also employed instead of
PbBr

2

in the Al–PbBr

2

–TFA redox system.

Avoid Skin Contact with All Reagents

4

ALUMINUM

OMe

Ph

OMe

Ph

OMe

OMe

Ph

OMe

PbBr

(16)

+

AlBr

3

(0.5 equiv)

THF

Ph

Ph

OMe

OMe

(4)

(7)

(5) 40%

Pb/Al

(6) 40%

An extremely facile procedure for C-allylation of imines in-

volves direct mixing of imines and CH

2

=

CHCH

2

Br with a cat-

alytic amount of PbBr

2

(0.03 equiv) and Al foil (1 equiv) in ether

containing Boron Trifluoride Etherate (1.1 equiv) (eq 17).

48

With

almost the same efficiency, aromatic and aliphatic aldimines un-
dergo electroreductive Barbier-type allylation using an Al anode/
PbBr

2

/Bu

4

NBr/THF/Pt cathode system where a combination of

sacrificial Al anode and Pb

0

/Pb

II

operates as a mediator for anodic

and cathodic electron transfer processes, respectively.

49

Cl

N

Ph

Br

Cl

N

H

Ph

+

PbBr

2

, Al, BF

3

·

OEt

2

ether, rt, 10 h

94%

(17)

Regarding the chemical allylation of imines, PbBr

2

and the

BF

3

·

OEt

2

couple can be replaced with a catalytic amount

(0.05 equiv) of Titanium(IV) Chloride. This system is highly ad-
vantageous in chirality transfer from

L

-valine into a homoallylic

amine (diastereomeric ratio greater than 20:1) (eq 18).

50

N

Ph

CO

2

Me

Br

HN

Ph

CO

2

Me

NH

2

Ph

1. OH

–

2. –e, –CO

2

81%

Al, TiCl

4

, rt

77%

(18)

Similar to the transformations observed for acetals,

46,47

intro-

duction of TFA in the Al–PbBr

2

system allows reductive dimer-

ization of N-alkylimines to vicinal diamines.

51

Reductive dimerization of allylic as well as benzylic bromides

is mediated by the Al–PbBr

2

system in DMF. In the case of allylic

bromides dimerization is complicated by allylic rearrangement
and gives a mixture of isomeric 1,5-hexadienes. Benzylic bro-
mides only give 1,2-diarylethanes.

52

The same reactions are also

induced by metallic Pb–Bu

4

NBr in DMF.

52

An Al/PbBr

2

/NiCl

2

(bipy) (molar ratio 0.7:0.1:0.1) system pro-

motes reductive dimerization of 2-arylvinyl halides to form 1,4-
diaryl-1,3-butadienes, precursors of terphenyl derivatives (eq 19).
The process is almost stereospecific and both double bonds in
the dimer retain the C=C bond configuration of the starting vinyl
halide. The reaction is carried out in DMF or MeOH at ambi-
ent temperature with KI (1.5 equiv) added. No dimerization is
observed if THF, MeCN, CH

2

Cl

2

, or C

6

H

6

are used as solvent

or in the absence of either NiCl

2

or PbBr

2

. The latter can be re-

placed by BiCl

3

, SnBr

2

, or GeCl

4

, but dimer yields are remarkably

decreased.

53

Ph

Br

Ph

Ph

Ph

Ph

HO

2

C

CO

2

H

Ph

Ph

CO

2

H

Al, PbBr

2

, NiCl

2

(bipy)

MeOH, rt, 6 h

83%

E,E

:E,Z = 97:3

1. maleic anhydride
xylene, 180 °C

2. aq KOH
82%

chloranil

xylene, 138 °C

81%

(19)

Both aromatic and aliphatic aldehydes undergo Al–PbBr

2

me-

diated reductive addition of polyhalomethanes CX

3

Y (X = Cl,

Br; Y = Cl, Br, CN, CONH

2

). The reaction (aldehyde:CX

3

Y:Al:

PbBr

2

= 1:2–4:1.2:0.1) is performed in DMF, yielding α-

(trihalomethyl) carbinols (8) in almost quantitative yield. These
can be subjected to further reductive elimination with Al–PbBr

2

in

MeOH containing aq HCl to produce 1,1-dihaloalkenes (9). When
carbinols (8) react in DMF, reduction of the trihalomethyl group
to a dihalomethyl occurs instead of elimination (eq 20).

54

This ap-

proach has been used in the stereospecific synthesis of pyrethroid
insecticide precursors

54

and arylacetic acids.

55

Cl

H

O

Cl

CCl

3

HO

Cl

CHCl

2

HO

Cl

Cl

Cl

+

CBrCl

3

Al–PbBr

2

(3:0.1)

DMF, rt, 5 h

86%

(8)

(9)

(10)

(20)

Al–PbBr

2

aq HCl–MeOH, 50–60 °C, 7 h

83%

Al–PbBr

2

DMF, rt, 4.5 h

64%

In the same way, a CF

3

CCl

2

unit can be introduced into alde-

hydes via a reaction with CF

3

CCl

3

. This process is chemospecific

and no adducts resulting from C–F bond cleavage are formed.

56

The Al–PbBr

2

system is also capable of mediating a facile

reductive removal of bromine atoms from 6-bromo- and 6,6-
dibromopenicillanate derivatives (in MeOH/aq 1% HBr (9/1)),

57

and has been used in prenylation reactions of p-benzoquinones
and naphthoquinones.

58

Aluminum–Bismuth(III) Chloride. Al powder in combina-

tion with catalytic amounts of BiCl

3

in aqueous THF at am-

bient temperature promotes efficient Barbier-type allylation of
aldehydes.

59

The reaction occurs with allylic rearrangement in

the entering unit and stereoselectively gives the erythro product.
The reaction involves allylbismuth reagent formation through the
oxidative addition of an allylic halide to Bi

0

generated by the re-

duction of BiCl

3

with Al. Metallic Bi is also capable of allylating

aldehydes to homoallylic alcohols in aprotic DMF, but not in an
aqueous solvent.

60a

Metallic Zn or Fe also can be used with BiCl

3

instead of Al.

60b

The system also induces alkylation of immonium cations. The

procedure is experimentally simple due to its being performed

A list of General Abbreviations appears on the front Endpapers

ALUMINUM

5

in aqueous media.

61

Among other alkylation agents, methyl and

benzyl halides have been used for the first time in this Barbier
reaction system (eq 21).

61b

N

H

N

N

N

N

N

N(i-Pr)

2

(21)

i

-Pr

2

NH, CH

2

O

N(i-Pr)

2

MeI, Al–BiCl

3

THF–H

2

O, rt

78%

Aluminum–Antimony(III)

Chloride

and

Aluminum–

Indium(III) Chloride.

Both systems promote Barbier-type

allylation of aldehydes. However, in contrast to InCl

3

, which is

required only in a catalytic amount for a reaction in aqueous
THF,

62

more than stoichiometric amounts of SbCl

3

are used in

DMF–H

2

O (3:1) and NaI is added to activate allylic bromides

(aldehyde:allylic halide:Al:SbCl

3

:NaI = 1:1.2:2:1.5:1.2).

63

Simi-

lar to the Al–PbBr

2

system,

58

Al–InCl

3

also mediates prenylation

of naphthoquinones.

62

Al in combination with a catalytic amount

of SbCl

3

induces acetalization of carbonyl compounds.

63

Aluminum–Nickel Alloy. In alkali medium this reagent is

employed for chemical reductions.

64

Al affects liberation of hy-

drogen which actually plays the role of reducing agent (eq 22).

NiAl

+

3NaOH

Ni

+

Na

3

AlO

3

+

1.5 H

2

(22)

Besides reduction of carbonyl compounds, organic halides, and

nitriles,

64b

in recent years numerous compounds containing N–N

and N–O bonds (hydroxylamines, hydrazines, N-nitrosoamines,
N

-oxides) have been reduced to amines.

65

A few heterocycles are

also reduced by this reagent, and high temperatures, high pres-
sures, or a hydrogen atmosphere are not required. Corresponding
tetrahydro derivatives are produced from pyridines, quinolines,
and pyrazines, whereas pyrimidines, pyridazines, oxazoles, and
isoxazoles undergo reductive cleavage of C–N, N–N, or N–O
bonds to yield saturated diamines or diamino alcohols (see Raney
Nickel).

66

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Avoid Skin Contact with All Reagents

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Emmanuil I. Troyansky

Institute of Organic Chemistry, Moscow, Russia

A list of General Abbreviations appears on the front Endpapers