Two new, crystalline solid, storable, and highly enantioselective reagents for aldehyde crotylation have been developed. Both (cis and trans) crotylsilane reagents are easily prepared in bulk, require trivial reaction conditions, and provide the homoallylic alcohol products with near diastereo- and enantiospecificity in many cases.

The development of reagents and catalysts for the enantioselective allylation of ketones has been an important goal in asymmetric synthesis for many years. Over the past decade, some important and seminal advances have been recorded, but most of these require the use of potentially toxic tin-based allyl reagents.[1] More recently, Chong, [2] Shibasaki, [3] Soderquist, [4] and Yamamoto [5] have recorded truly remarkable advances. With only a few notable exceptions, however, the scope of reactions that gives useful levels of efficiency and enantioselectivity remains limited to aryl methyl, cyclohexenyl methyl, and tert-butyl methyl ketones and structurally related derivatives thereof. There is no current solution at all for the enantioselective allylation of several important classes of ketones, including highly sterically hindered aryl alkyl ketones and diaryl ketones. In addition, only limited success has thus far been recorded in enantioselective ketone crotylation reactions, and no method that can produce both the syn and anti diastereomers with high levels of diastereoand enantioselectivity has been reported. Our own recent investigations into the use of strained allylsilanes [6] for enantioselective aldehyde allylations and crotylations [7]

No abstract

The development of reagents and catalysts for the enantioselective allylation of ketones has been an important goal in asymmetric synthesis for many years. Over the past decade, some important and seminal advances have been recorded, but most of these require the use of potentially toxic tin-based allyl reagents.[1] More recently, Chong, [2] Shibasaki, [3] Soderquist, [4] and Yamamoto [5] have recorded truly remarkable advances. With only a few notable exceptions, however, the scope of reactions that gives useful levels of efficiency and enantioselectivity remains limited to aryl methyl, cyclohexenyl methyl, and tert-butyl methyl ketones and structurally related derivatives thereof. There is no current solution at all for the enantioselective allylation of several important classes of ketones, including highly sterically hindered aryl alkyl ketones and diaryl ketones. In addition, only limited success has thus far been recorded in enantioselective ketone crotylation reactions, and no method that can produce both the syn and anti diastereomers with high levels of diastereoand enantioselectivity has been reported. Our own recent investigations into the use of strained allylsilanes [6] for enantioselective aldehyde allylations and crotylations [7]

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