Allylsilanes

Scheme 45 Formation of 1,3-Disubstituted Allylsilanes by Decarboxylative Elimination
[165,166]
R 1
95
CO 2R 2
LDA, −78 o C
1. Li2[Cu(CN)(SiMe2Ph) 2]
2. NH4Cl PhMe 2Si OR 2
R 1
(Z)-97
ester cleavage R 1
R 3
R 1
OLi
SiMe 2Ph
99
R 1
CO 2H
OH
SiMe2Ph
96
CO 2R 2
R 3 CHO R 1
Method A
Me2NCH(OMe) 2
CHCl3, reflux, 5 h
SiMe 2Ph
R 1 R 3 Method Configuration
of 101
R 3
Method B
PhSO2Cl, py
0 oC, 12 h
R 3
SiMe 2Ph
3
2
1
98
CO 2R 2
OH
R 1
R 1
SiMe2Ph O
R3 100
R 3
O
collidine
reflux
SiMe 2Ph
(E)-101 (Z)-101
Yield (%) a
of 101
Ph Me A E 85 [165]
Ph Me B Z 51 [165]
Me Ph A E 87 [165]
Me Ph B Z 81 [165]
Me iPr A E 91 [165]
b [165]
Me iPr B Z 47
iPr Me A E 88 [165]
c [165]
iPr Me B Z 59
a From 99.
b 16% E contamination.
c 11% E contamination.
FOR PERSONAL USE ONLY
870 Science of Synthesis 4.4 Silicon Compounds
Conversion of â-Hydroxy Acids 99 into E-Allylsilanes (E)-101; Method A;
General Procedure: [166]
Me 2NCH(OMe) 2 (0.72 g, 6 mmol) and â-hydroxy acid 99 (1 mmol) were refluxed in dry
CHCl 3 (20 mL) for 5 h. The solvent was removed in vacuo and the residue was flash chromatographed
(silica gel, hexane) to give the E-allylsilane.
Dimethylphenyl[(E)-1-phenylbut-2-enyl]silane [(E)-101, R 1 = Ph; R 3 = Me]; yield: 85%.
Sarkar, T. K., SOS, (2002) 4, 837. 2002 Georg Thieme Verlag KG
Ref