Catalysis of the Michael reaction

oo40-4039/85 $3.00 + .oo 01985 Pergamon Press Ltd.

Tetrahedron Letters,Vo1.26,No.22,pp 2645-2648,1985 Printed in Great Britain

CATALYSIS

OF THE MICHAEL

REACTION

Pierre Laszlo:: and Pascal Pennetreau

Institut de Chimie Organique Universite

de Liege au Sart-Tilman

4000 Liege,

: Two nearly equivalent

Abstract Michael

reaction

supported Michael

additions

acceptor

atom,

synthon

a

carbons

usually

required importance

These

deposited

catalysts

will

: the latter, an activated

separate

electronic oxygen,

the

migrates

of Michael Side

and coupling

additions

undergo

reactions

to

a carbanionic

olefin,

from carbon

catalysis and

donor

is typically

the

and

enable

A

sufficiently

are

aldol

synthon

an even

During

methylene

methylene

number

of

the course of

to a better

stabilized

addition

d and an

an a,b-unsaturated

Hence,

in the donor

with its activated

2645

of

(ii) alumina-

turnovers

also from their being component

be avoided

of the carbanion

150t

and the electrophile.

electrophile.

stems

for

on xonotlite;

to aldol addition.

the nucleophile

charge in

vinylogous

evolved

or below in good yields.

form a new C-C bond between

the addition

been

: base serves to form the donor from the activated

annelationsIm3. synthon),

fluoride.

reactions

the reaction,

have

to be run at room temperature

ketone, which makes interposed

procedures

: (i) potassium i-butoxide

potassium

MICHAEL

Belgium

acceptor

carbanion precursor.

is The

parts of Robinson

(A~

rather

precursor.

than

-a3

2646

We have Diels-Alder

a general

alone

at improvement

cycloadditions4-6,

ture or below, using reaction,

program

because

only

to make

low-cost

of important

them efficient

reagents

organic

reactions,

and selective

at ambient

and materials.

it is one of the sacred cows of organic

? It is nearly a century-old

(1887)

We latched chemistry

upon

such

as

tempera-

the Michael

: should it be left

: it is ample time to devise catalysts

for it,

we feel.

which

Rational

design

of a catalyst

could

be further

to dump the abstracted type,

with

their

were evolved

use alumina'

(a solid

use the new have

made

catalyst

acid

by doping

is prepared

yet

need

of inorganic

for this ancillary

here

supports

role;

them with strongly

which

contains

intrinsic

by

by dissolving

by adsorption

xonotlite

adsorption

basic

10

of i-butoxide

t-BuOK

basic

oxide

function

centers.

is further

120°C; it can be stored at room temperature

are indicated

already

from

(3,6 or 9 g) in -t-BuOH

is eliminated

at 6O'C. The catalyst

sites

ions

and -t-BuOH

evaporator

using both procedures,

of the metallic

, a basic support

connected

Results,

areas in which

of fluoride

vigorously

bath

storage

basic anionic

is stirred

on a water

a Brb'nsted base,

the primary

te (159) is added and the mixture to a rotary

for

:

aluminosilicate

basic

the

it with neighboring

*,') and boost the basicity

calcium

more

by providing

oxygens

Two solutions

to answer

: we thought

we figured,

aldol reactions

B.

protons

numerous

could be fulfilled,

A.

improved

has

also,

which

KOC(CH3)3.

we The

(ZOO ml); xonotliThe flask is

reduced

pressure,

dried for one night in an oven at

and is stable for several months.

below

in

ions from KF;

for 5 minutes. under

used

(Table 1).

2647

acceptor

donor

reaction

acetylacetone

methylvinylketone

(5OmM)

(50mM)

ethylacetoacetate

methylvinylketone

(5QnM)

(50mM)

diethylmalonate

methylvinylketone

(50mM)

(50mM)

acetylacetone

acrolein

(50mM)

(50mM)

ethylacetoacetate

acrolein

(5OmM)

(50mM)

diethylmalonate

acrolein

(50mM)

(50mM)

dimedone

methylvinylketone

yieldsa

2OCmg B(6/15)b,THFC,r.t.,4d

79%

200mg B(3/15),THF,r.t.,3d

70%

200mg B(3/15),THF,r.t.,3d

70%

200mg B(3/15),THF,0°,24h

74x::

1OOmg B(3/15),THF,0°,24h

62%':

200mg B(9/15),THF,0°,4d

60%':

50mg A" ,THF,r.t.,3d

100%

(10mM)

(IQ'iM)

a. Isolated yields,

except::, from GC integration

b. y/15 = t-BuOK/xonotlite c. in CH2C12,

Table 1

conditions

90% yields

(w/w) are achieved

after 20h of reaction

at r.t.

: Michael additions with catalysis by basic inorganic supports.

Based upon the quantity

of the catalyst

effected.

We feel that

this method

including

some recent attempts

used, a minimum

is a significant

at catalysis

12,13

.

of 150 catalytic

improvement

cycles

over existing

are

methods,

2648

Acknowledgments

:

We thank Dr. A. Mathy for

xonotlite,

grateful

References

W.S.

the

Eternit

to Programmation

of this work

1.

and

of this

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de la Politique

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gift

of

Scientifique,

the t-BuOK samples

doping

procedure

of xonotlite.

Brussels,

for generous

We are support

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2.5, 1885