Peterson alkenations 1 - cyclopropane

Homo-Peterson Alkenation. Styrene oxide reacts with lithio-phenylthiobis(trimethylsilyl)methane to afford cyclopropane-containing products (eq 6)7 This reaction is limited, due to the complexity of its mechanism the alkenation reagent must serve to generate both alkenic and carbenic species. For this reason, only styrene oxide and trimethylsilyloxirane undergo this transformation. 

Peterson alkenation cyclobutane synthesis and cyclopentane annulation via l-lithio-l-(trunethylsilyl)cyclopropane)... 

Peterson Alkenation. l-Lithio-l-(trimethylsilyl)cyclopro-pane, derived from l-phenylthio-l-(trimethylsilyl)cyclopropane by reductive lithiation with lithium l-(dimethylamino)naphtha-lenide (LDMAN), condenses with aldehydes to give carhinols which are converted to alkylidenecyclopropanes under Peterson alkenation conditions (eq 1). ... 

Addition of dimethylsulfonium methylide (122) to various Michael acceptors (121), followed by alkylation, has been reported to produce functionalized 1-substituted alkenes (124), arising via the unprecedented elimination (123), rather than the usual cyclopropanation products. In silyl substituted substrates, where a facile Peterson-type olefination is possible from the adduct, elimination took place instead. Aryl-substituted Michael acceptors (121 R1 = Ar) underwent a similar olefination to give 1-substituted styrene derivatives with moderate yields along with a side product, which arose by nucleophilic demethylation from the adduct of dimethylsulfonium methylide and arylidene malonates. Hammett studies revealed that selectivity for olefination versus demethylation increases as the aryl substituent becomes more electron deficient.164... 

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