Formation and oxidation of sp3 C-Si bonds

Question 1

How do phenyldimethylsilyl nucleophiles react?

Answer 1

In a 1,4 fashion (soft Nu so conjugate addition)

Question 2

How does migration occur in Tamao and Fleming oxidation?

Answer 2

Stereospecific with retention of config. at migrating centre

Question 3

How are silylcuprates and silylzincates prepared?

Answer 3

Made in situ from phenyldimethylsilyllithium. Silylzincate tends to be more reactive and often gives better yields c.f. silylcuprate. PDMS itself reacts in 1,2 fashion with a,B unsaturated carbonyls to make silyl carbinols.

Question 4

What are 2 approaches to C-Si oxidation to C-O?

Answer 4

1. Tamao - EN atom already present. 2. Fleming - heteroatom incorporated in a first step by electrophilic desilylation (usually of Ph)