1,1‐Disilyl‐2‐Alkenes: Preparation and Some Synthetic Applications. Preliminary communication

Abstract

SummaryAlly1 sulfides and a selenide are metallated and silylated with chloro (pentamethy1)disilane. Treatment of the resulting disilanylmethyl sulfides 4 with trimethyloxonium tetrafluoroborate furnishes l,l-disilyl-2-alkenes 5 in good yields. Some synthetic possibilities of 5 are outlined.The synthetic utility of allylsilanes 1 and vinylsilanes 2 has been amply demonstrated [ 11 (Scheme 1). Whereas there are convenient methods to prepare vinylsilanes2), routes to allylsilanes3) are mostly complicated and often leading to mixtures. We describe an easy way to convert allyl sulfides 3 and an allyl selenide via the corresponding disilanes 4 to substituted l,l-disilyl-2-alkenes 5. Based on the observation by Kumada of a facile disilane-disilylmethane rearrangement4) the Schema I

Stereoselective Peterson Olefinations from Bench‐Stable Reagents and N‐Phenyl Imines

“…An alternative approach to the generation of the α‐silyl carbanions that does not require strong bases is to use geminal bis(trimethyl silanes) 4 as starting substrates and a fluoride source to promote generation of the α‐silyl carbanion precursor 5 (Scheme , route b). Bis(silanes) 4 are bench stable (analogous to the Wittig phosphonium salt), yet they have received very limited use due to the lack of a general route for their synthesis 4e–g. 6 The use of bis(silanes) as Peterson olefination reagents offers an additional advantage in that they eliminate the need to pre‐form the carbanion species as it is generated in situ in the presence of the aldehyde.…”