AD-AO81 936 MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CHEMISTRY FIG 7/3NEW FUNCTIONAL ALLYLIC LITHIUM REAGENTS? GEM-DIALKOXYLLYLLITHI...TC(U)1979 D SEYFERTH, R E MAMMARELLA. H A KLEIN N0001-76-C-0637UNCLASSIFIED

ML

m'IIIIIIIIIIII lfflll

MsnoxAL.AT.T.YL 1R ENTNh NA q- A

D~~p== oAM offl WhIMY .-, it'RKAGEN A RISZFUL TO "LADNTNYPROPICNT SES

e STh ferth j Robeit E./Mammarella a Helmut A Klein /Department of Chemistry

4Massachusetts Institute of TechnologyCambridge, Massachusetts 02139

The reaction of j=-butyllithiuM with acrolein dialkyl' acetalsin THF or in THF/EtJO/pentane at -9 results in formation of SM-

dialkoxyallyllithium reagents, LiECHJCHC(OR)-]. These react with

S organosilicon and organotin chlorides to give ketene acetals,

R 3SiCH2CH=C(OR)2 and R3SnCH2CH--C(0R)2 . The acid hydrolysis of these

products produces /G-substituted propionic acid esters, R3SiCH2-

CH2CO2R and R3SnCH 2CH2CO2R. Reactions of these lithium reagents

with allyl bromide gave esters of 5-hexenoic acid, CH2=CH(CH 2 )3-

C02R (R = Me, Et).This document has been approvedfor publtc relocm and sale; Its

- distribution Is unlimited.Contract!N 6 4-76,C-,O .. . .

2 19 076

INTRODUCTION

The lithiation of allylic ethers provides useful reagents

which are operationally equivalent to a /-acyl carbanion (eq. 1-3) 1.

-65 0CROCfl2CH-CH2 + sac-Cj4,k9i )p* LirCH2 CHCHORJ + Colo0 (1)

THF

Li[CH2cHCHO + RIX -- R'CH2 CHCHOR + CH2,CHCH(R')OR (2)

R"CH2CH=CHOR + H20 - R'CH 2CH2C(O)H + ROH (3)

In this context, the possible lithiation of an allylic acetal,

CH2-CHCH(OR)2, was of some interest. The expected product is a anm-

dialkoxyallyllithium reagent (eq. 4) which potentially could react

CH2 =CHCH(OR) 2 + R'Li Li LI[CH2 CHC(OR) 2] + A (4)

with an electrophile, E, at either the unsubstituted or the substi-

tuted terminus of the allyl group (eq. 5). If the new bond is formed

H30

ECH2CH=C(OR)2 NO- ECH2CH2COR

Li CH2CHC (OR)] E C3=HC ) 30+ 0

CH2=CHC (0R), 2 Ch2=CHCE

E 0

at the substituted end, an allylic acetal would be formed. Hydrolysigs

of the latter would give a vinyl ketone. In this case the reagent

would function as a carbonyl anion equivalent, CH2=CHC(O)'. If, on

the other hand, the new bond is formed at the unsubstituted terminus of

the allyl group, a r-substituted ketene acetal would result. Hy-

drolysis of such a product would give an ester, as shown in eq. 5. In

L J, .L_-: __ _::: - :...... .... ......

-3-

this case the reagent would be operationally equivalent to a--

koxycarbonyl carbanion, ROC (0)CH2 CH2

Of special interest to us were the reactions of such Li

[CH 2 CHC(OR) 2] reagents with organometalhic halides, in particular

trimethylchlorosilane and trimethyltin chloride. Alkyl- and aryl-

substituted allylic lithium reagents of type Li H CCHCHaR and Li

[H 2 CHCR22 had been found to react with both of these halides to give

exclusively products of structure Me3MCH 2CHCHR and Me3MCH2CH-CR 2

(M = Si and Sn), respectively.2'3 On the other hand, trimethylchloro-

silane reacted with SeM-dichloro-4 and Ln-difluoroallyllithium5 to

give Me3 SiCX2 CH-CH2 (X = Cl and F). Trimethyltin chloride formed

Me SnCH on reaction with In the case of the

Me 3SiCI reactions it was quite likely that products of kinetic con-

trol were obtained, while those derived from Me 3SnCl were products of

thermodynamic control.4

In view of the potential synthetic utility of reagents of

LiLCH2CHC(OR) 2 J and in view of the uncertainty of the regioselectivity

* in their reactions with various electrophiles, we have investigated

their synthesis, stability and, to a limited extent, their reactions.

RESULTS AND DISCUSSION

We have found that acrolein dimethyl and diethyl acetals may be

lithiated by sge-butyllithium in a THF/diethyl ether/pentane solvent

mixture at -90 0 .50 C to give a yellow solution containing the re-

spective &e=-dialkoxyallyllithium reagents (eq. 4, R = Me and Et; R'

se=-C 4H9 ). The temperature range for successful preparation of these

reagents is quite narrows below -1000C the metalation reaction ap-

pears to be too slow; above -85 0 C the reagents begin to decompose

slowly. Their decomposition is rapid at -65 0C and above. Nonethe-

less, they find useful applications in synthesis.

We have thus far studied the reactions of these new allylic

lithium reagents with several organosilicon and organotin chlorides

and with allyl bromide (Table 1). Such reactions of Li H 2CHC(OR)2]

with orgarosilicon and organotin chlorides, followed by nonhydro-

lytic work-up, gave silicon- and tin-substituted ketone acetals as

the exclusive products (eq. 6). These acetals are acid-sensitive and

Lij[H2CHC(OR)2] + R'3C1 - R'3MCH2CH-C(OR)2 + LiCl (6)

(M - Si, Sn)

decompose slowly on standing.

The reaction shown in eq. 6 thus provides a useful new route to

substituted ketene-O,O-acetals. Such reactions of g-dialkoxyallyl-

lithium reagents with silicon and tin chlorides, when followed byprovide

hydrolysis of the initially formed products.,a new synthesis of

silyl- and /3-stannylpropionic acid esters as shown in eq 7. The

LiICH2CHC(OR)I] + R' 3Mc). -4 3 R' MCHC2O2 + ROH + LiCi.(7)

yields of these products ranged from moderate to excellent. The con-

ditions required for hydrolysis of the initially produced acetals

differed for the reactions with organosilicon and organotin chlorides,

In the case of the former, hydrolysis with neutral water was suffici-

ent to give complete conversion to the esters. The organotin-substi-

tuted acetals were only incompletely hydrolyzed on treatment of the

reaction mixtures with neutral water. Hydrolysis with 5%, or better,

10%, aqueous hydrochloric acid was required for production of the

tin-substituted ester. The explanation for these observations is a

simple one. Hydrolysis of unreacted chlorosilane, generally added in

excess, generates an acid medium which facilitates hydrolysis of the

#4I"4

4A

".4 0 C.4-_ m L%-4 No0-

5.4- 4 N 'cO 0 '04 ~CM 4s N N 0

31 0 X ~ -0 N 4 4 N 0J 4- = 4a% 'E-1 >4 N N CM 04 N cmh

0 0 3 0 N 00t) ci 0 % 0+ =. NE4 ?I 14 4.m

"4~c N4 NB N Ih 0 N=h i0 h14 ~ O 0 NO N 00 N N N N,4

0I 00 NO 0 C3 00 m 0, ~N N =0 N = 00 cm NO4 OC3

WI Q 0. V N- 0 NOI 0 ta

k 0 cr "4% N 40 00 4a

o- CO XO Xi Of 01" nO C'O 0 O O COC

.0

4.'

"410

I 0 F-4 0 0 0 r 0 0

C.. N cm VN

0%"I 3: ZD %H+4 N 1. V- 0 0 0 0 N 5. LHd NQC N Nt Go '0C %0

H- H. NH. "40 H.. H- % 4 H H H0 N NH- 4-' 0.0

HO C3 0 E C0f C "4r N"4 W4 NC ~

on' 4) CI4 ) 4 4) COO COCO 4)OC IIa) 0 Da0 E h 04M MM x 00a

10 f-

0 H +

0-- HN go-% N ~

0 CH0 0 0 0 0 a ' 4 0 4' 0' 4 0 4'

-4 0 0

i -6-

TABLE I: Footnotes

a Prepared at -900 5°C by reaction with sec-butyllithium.

b A 1211 mixture of Me3SiCH2CH--C(OMe) 2 and Me3 SiCH 2CH2CO2Me was

produced.

C The Et SiOSiEt formed on hydrolysis of unconverted Et3 SiCl can-:3 :33

not be separated from the product and so it is better to use an

excess of the lithium reagent.

d By-products included the respective disiloxane in those reactions

in which an excess of the chlorosilane was used.

~-7-

acetal. Organotin chlorides, on the other hand, do not hydrolyze

readily. Although their rate of hydrolysis is rapid, the hydrolysis

equilibrium is not favorable. 6 Hence, insufficient acid is generated

and external acid must be added to effect hydrolysis of the acetal.

The formation of products of type R'IMCH2CH=C(OR)2 rather than

R'3IC(OR)2CH=CH2 in these reactions of Li H2CHC(OR)2J with R'3lI

may be understood in terms of the operation of steric effects. It is

unlikely that allylic organosilicon compounds of either type (M = Si

in the formulas above) would take part in transmetalation equilibria,

so we assume that we are dealing with products of kinetic control.Products of type R' 3SiC(OR)2CH=CH 2 would have been of some interests

their hydrolysis should have given 0-silyl ketones, R'3SiC(O)CH--CH 2.

Other methods for the preparation of /6-silyl- and -stannyl-

propionic acid esters are available. Such silyl-substituted esters

can be prepared by the acetoacetic ester and malonic ester syn-

theses when the appropriate halomethylsilanes, R3SiCH 2X, are avail-

able. 9 Both silyl and stannyl-substituted esters have been prepared

by silicon or tin hydride addition to acrylate esters,10-13 whileof

the reaction3-halopropionic acid esters with tin foil provided

another route to /I -stannyl-substituted esters.14 Thus the present

procedure, which is based on the availability of the silicon or tin

halide, complements these procedures.

-8-

General Comments.

All reactions were carried out in flame-dried, nitrogen-flushed

glassware under an atmosphere of prepurified nitrogen or argon. Sol-

vents were rigorously dried prior to use. The reaction temperatures

which are reported AM re DreTJgd. They were obtained using a pen-

tane total immersion thermometer which was immersed to a depth of

about 3 cm into the stirred reaction mixture. Experiments showed

that a stem corrction of -8 to -10°C is appropriate.

sec-Butyllithium was purchased from Alfa Products, Thiokol/Ven-

tron Corp., chlorosilanes from Petrarch Systems, Inc., the acrolein

dialkyl acetals from Aldrich Chemical. Co. Methyltin starting mat-

erials were kindly donated by Cincinnati Milacron Chemicals, Inc.

Infrared spectra were recorded using a Perkin Elmer Model 457A

grating infrared spectrophotometer, NR spectra with a Varian Assoc-

iates T60 spectrometer. Gas-liquid chromatography (GLC) was employed

for analysis of reaction products, isolation of product samples and

for yield determination by the internal standard method.

j. _ _ _ _ _ _|S

-9-

Preparation of em-Dialkogyalllithium Reagents, General Pro-

A Morton (creased) flask of appropriate size equipped with

a paddle-type stirrer, a no-air stopper and a Claisen adapter which

was fitted with a low temperature thermometer and a gas inlet tube,

was flame-dried bnd then allowed to cool under a stream of nitrogen

or argon. The flask then was charged with the solvent mixture

(75 ml of THF, 15 ml of diethyl ether and 15 ml of pentane), 21 mmol

of the acrolein dialkyl acetal (2.5 ml in the case of CH2--CHCH(OMe)2 )

was added, and the solution was cooled to -900.0 50C by partial im-

mersion in a liquid nitrogen Dewar flask. To this solution was added

with stirring and under nitrogen (or argon) 20 ml of 1.1X sec-butyl-

lithium in cyclohexane (22 mmol). The temperature was maintained

at -900- 50C during the course of this very slow, dropwise addition.

The resulting yellow solution was stirred 2-3 hr. at -900C.

To this reagent solution then was added the chlorosilane or the

tin chloride (slight excess, ca. 25-30 mmol) by syringe over a 10

min. period. The resulting mixture, now milky white, was stirred at

-90 C for 30 min. and then was allowed to warm to room temperature.

In the non-hydrolytic work-up, the reaction mixture was trans-

ferred by cannula to a dry distillation flask. Solvents were removed

at reduced pressure and the residue was trap-to-trap distilled at

ca. 0.1 mm Hg into a flask cooled with liquid nitrogen. The dis-

tillate then was examined by GLC.

In the hydrolytic work-up, the cannulated solution was poured

into a separatory funnel and treated successively with distilled

water, two portions of 5 or 10% hydrochloric acid and, again, water.

The aqueous phases were back-extracted with pentane and the com-

bined organic phases were dried (MgSO4 ) and the solvents removed at

.... ,, ..... ... .... ... .. ... .. ... ..... ili ll .... ..... .i.... .. . . .. .... " .... .. .. .. ..." ... . ... ... .... .. .... .. .......

-10-

reduced pressure. The residue was trap-to-trap distilled, as above.

Some reactions were carried out on a larger scale (42 mmol

of CH2 --CHCH(OMe) 2 , 63 mmol of CH2 --CHCH(OEt) 2 ). In some cases THF

alone, rather than the mixed solvent system, was used, but the mixed

solvent is preferred.

r"anos d 0 i" Products Characterization.

Table 2 lists the organosilicon and organotin esters and

acetals prepared, their refractive indices, analyses and spectro-

scopic properties. The infrared spectra of the esters (liquid film)

showed strong ester carbonyl absorption at 1735-1740 cm" . The

ketne acetals showed strong bands in their IR spectra at 1675

(Me SiCH CH=C(OMe) 2 ) and 1670 cm- 1 (Me SnCH2CH=C(OMe)

The methyl and ethyl esters of 5-hexenoic acid are known com-

pounds.

CH2=CHCH 2CH2CH2CO2 Me, n2 D 1.4205 , a known compound.

IR (film)s ')(C=O) 1755, N(C=C) 1640 cm"1 .

NMR (CDC1 3 ): 1.6-2.5 (m, 6H, CH2 CH2 CH2 ), 3.6 (s, 3H, CH3 ) and

4.75-6.3 (m, 3H, CH=CH2 ).

CH2=CHCH 2CH2CH2C02Et, n2 0D 1.4225; lit. 8 n 2 0D 1.4220

IR ffilm), t (C=O) 1735, (C=C) 1640 cm "1 .

NNR (CC14 ): & 1.22 (t, 3H, J 7Hz, CH3 ), 1.48-2.03 (m, 2H, CH2 CH2.10 and 2.22 (2t, 4H, J 7Hz, CH2CH2C_2 ); 4.03 (q, 2H, OCH2), 4.73-

6.17 (m, 3H, CH=CH 2 ).

Acknowlediments. This work was supported in part by the Office of

Naval Research. H.A.K. is grateful to the University of Kiel for

a leave of absence and to the Max Kade Foundation for the award of a

postdoctoral fellowship.

04N~ ~ - N= . .a cm

04 00 (a-O O ~ N* ~ ~ ~ C -r40. ~ *

= C12 cm C3 Ca 4NJ4

0 t) Ul %- '0 0 0 N 0an V-1 * r cm CM r ~

00 0 \0 C_~ ~0 .~ +'tn ON U2 -0 4 0N

0 .'- n N0 an aU1

ca4 * N4 4n~ I CM I nE a - 8

4)-f (D =0 AN Sz '0 '-Ij N*,COl H C x N .. N tA

r0 NQ NO a = O.ZaP4 04 E .- a- C-0134 ~ 0.... 0

\20 a0 a, 4 * a 02 2cm CO cm UN 00 F N C-4 o Io

0 r3- = . C; e- n"4. 0 M' M - oa N ;o. .)g ri 0 N oU2~ U2C' 0 1.C NC, =,I ON 4-~ O

0 C* \* C)\. \0 Nl 0- * ** N-4

0 00 0 *l s 00 t 4* 00

a >

* 0 4.l NN L- %-~ CC)-a 0 0

0 0

0. U"-U)INVA ' l 0 \0 - l 0 \

N 04 N1 N* N~

o 0 'ca\.* 2 .. 0 O 0 ~

r. V-4

0

m cm ('M43 0 Nm 0 0 0V Nm 0 N 0 m N

cd00 a 00N NM 0 c

0

0 N \ P..

4) (D 4-). 43)K- 4 T

coob ~ ~ ~ 4 C=4 C- ~n S '~S

*n 0 M *4CQ 4a. 01 0 a% a = caG

a- C'N N CO V-4 0 - c- "0 r5 ILI . 40 r

S0- . GO2 MI %

-r W% 0~r P-4~

&0 4 0.. +3SIi-

04 N . n o Ci C # 0 U-% C - N Cr (n 4J2 I

N *VNA vi 00f cm

v4Q =N q 0 O0- 0 - - -ii UItN N VI

- q C~.~ - ~I *4 N~ - M S .'QN . 0%4 00' 0 ~ N

;,r -i4 = -- - 4 . =v

N4 n~ co Cui CN0 0 0n ui - 0 - 0 -0 a 0 u 0 iti

ON = 4~ ON :9 - =~ 0 0 0'- 0NC-i

N 0 cq 0 --t0 4 A

Cu 00 NV 0 0Uri n a4 u- % co 0 0

0 0 :9 N O C- 0%4 -4

\0 4. cnUN '

Nl 00.4'-4 m% NO

0 WE-'

0 00

"4

E~c cn- uic-

W! W 3E

Cm ~N

C34 A 0

02 0

0% ChU* v

02 %nC A*

~0 itq CCa v8 W4 N 2 ~ ~ N'

06 Nm U=N (m4 C C% 00V

4; r C4 M 4 4 1 ;+14. *.* C- CO ~ '4m

= - NQC;4 =' co c-4

%04

', -

.I~4 CCV- ~

N 4-DC;.

'4 en

0

0~~ Acesin0o*j * D* TANB

- T '4

'14 0-Q Dat cccj0Cm

46'

I, C4 C

-14-

REFERECES

1. (a) D. A. Evans, G. C. Andrews and R. Buckwalter, J. Amer.

Chem. Soc., 96 (1974) 5560, (b) W. C. Still and T. L. Macdonald,

J. Amer. Chem. Soc., 96 (1974) 5561, (c) W. C. Still and T. L.

Mcdonald, J. Org. Chem., 41 (1976) 3620; (d) A. P. Kozikowski

and K. Isobe, Tetrahedron Lett. (1979) 833.2. D. Seyferth and T. F. Jula, J. Organometal. Chem., 66 (1974) 195

3. D. Seyferth and R. E. Mammarella, J. Organometal. Chem., 177

(1979) 53.

4. D. Seyferth, G. J. Murphy and R. A. Woodruff, J. Organometal.

Chem., 141 (1977) 71.

5. D. Seyferth and K. R. Wursthorn, J. Organometal. Chem., 137

(1977) C17.

6. R. H. Prince, J. Chem. Soc. (1959) 1783.

7. P. Baudart, Bull. Soc. Chim. France (1946) 86.

8. Yu. N. Ogibin, M. I. Katzin and G. I. Nikishin, Synthesis (1974)

889.

9. L. H. Sommer and N. S. Marans, J. Amer. Chem. Soc., 72 (1950)

1935.

10. J. L. Speierj J. A. Webster and G. H. Barnes, J. Amer. Chem.

Soc., 79 (1957) 974.

11. G. J. M. Van der Kerk and J. G. Noltes, J. Appl. Chem., 9 (1959)

106.

12. F. Rijkens, M. J. Janssen, W. Drenth and G. J. M. Van der Kerk,

J. Organometal. Chem., 2 (1964) 347.

13. R. E. Hutton, J. W. Burley and V. Oakes, J. Organometal. Chem.,

156 (1978) 369.

14. M. Nomuri, N. Matsui and S. Matsuda, Kogyo Kagaku Zasshi, 71

V (1968) 1526, Chem. Abstr., 70 (1969) 47572.

00

-15-

115. A. D. Petrov, S. I. Sadyich-Zade and E. 1. Filatova, Zh. Obshoh.

Khim., 29 (1959) 2936.

16. N. V. Komarov and N. V. Semenova, Zh. Obshch. Khim., 36 (1966)

103.

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