C2-Symmetrical Silaketals and Applications

Evans and Murthy were the first to demonstrate the synthetic potential of silaketal intermediates in the TST-RCM with the construction of C2-symmetrical derivatives (Table 8.1) [13]. A series of enantiomericaUy enriched allylic alcohols were treated with dichlorodiphenylsilane and 2,6-lutidine to furnish the bts-alkoxysilane intermediates, which were subjected to RCM utilizing Grubbs first-generation catalyst [Ru]-I, to provide the corresponding silaketals in excellent yield (entries 1-5). This study demonstrated that the diphenyl-substituted silaketals were stable and that the reaction tolerates a variety of allylic alcohol substituents to provide a general approach for the construction of C2-symmetrical silaketals. 

liis-alkoxysilane DPSK, diphenyl silaketal Npth, 2-Naphthyl TBDPS =(-BuPh2Si. 

6 in good overall yield. Cleavage of the silaketal 6 with TBAF followed by the acetylation of the diol furnished the fcis-acetate 7 in 96% yield. This set the stage for the Ireland-Claisen rearrangement with the homotopic esters. Treatment of 

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