Novel DMAP-Catalyzed Skeletal Rearrangement of 5-exo-(2-Hydroxy- ethylene)oxasilacyclopentanes
摘要:
[GRAPHICS]5-exo-(Hydroxyethylene)-2-oxa-1-silacyclopentanes are found to undergo a novel DMAP-catalyzed skeletal rearrangement through silicon-oxygen exchange during acetylation to yield the corresponding 5-(2-acetoxyalkyl)-2-oxa-1-silacyclopent-4-enes exclusively. The mechanism for this unprecedented rearrangement is proposed.
Desymmetrization of 4-Dimethylsiloxy-1,6-heptadiynes through Sequential Double Silylformylation
摘要:
[GRAPHICS]Desymmetrization of dimethylsilyloxyalkadiynes (1) by Rh-catalyzed intramolecular silylformylation affords 5-exo-(formylmethylene)-oxasilacyclopentanes 2 in high yields. Novel sequential double silylformylation of 1a also provides desymmetrization, giving 3-(3-silyl-2-formylprop-2-enyl)-5-exo-(formylmethylene)oxasilacyclopentanes 4 in excellent yields. Reduction of 2a and 4 with NaBH4 gives the corresponding 5-exo-(hydroxymethylmethylene)oxasilacyclopentanes 3a and 5, respectively.