384378-15-8Relevant academic research and scientific papers
Palladium-catalyzed asymmetric diene cyclization/hydrosilylation employing functionalized silanes and disiloxanes
Pei,Widenhoefer
, p. 7639 - 7645 (2001)
Pentasubstituted disiloxanes and silanes of the form HSiMe2CHxPh3-x (x = 1 or 2) reacted with dimethyl diallylmalonate (1) and other functionalized 1,6-dienes in the presence of a catalytic 1:1 mixture of (N-N)Pd(Me)Cl [N-N = (R)-(+)-4-isopropyl-2-(2-pyridinyl)-2-oxazoline] [(R)-2] and NaBAr4 [Ar = 3,5-C6H3(CF3)2] to form the corresponding silylated cyclopentanes in good yield with high diastereoselectivity. The enantioselectivity of cyclization/hydrosilylation of 1 with disiloxanes and functionalized silanes at -20 °C increased in the following order: HSiMe2OSiMe3 (75% ee) 2OSiMe2-t-Bu (80% ee) 2OSiMe3 (86% ee) = HSiMe2Bn (86% ee) 2OSi(i-Pr)3 (89% ee) 2OSiPh2-t-Bu (91% ee) 2CHPh2 (93% ee). Silylated cyclopentanes derived from HSiMe2OSiMe3 were oxidized with excess KF and peracetic acid at room temperature for 48 h to form the corresponding hydroxymethylcyclopentanes in good yield (82-95%). Silylated cyclopentanes derived from HSiMe2OSiPh2t-Bu were oxidized with a mixture of tetrabutylammonium fluoride and either H2O2 or peracetic acid to form the corresponding alcohols in 48-76% yield. Silylated carbocycles generated from benzhydryldimethylsilane were oxidized with a mixture of TBAF/KHCO3/H2O2 in 71-98% yield. Asymmetric cyclization/hydrosilylation/oxidation employing benzhydryldimethylsilane tolerated allylic and terminal olefinic substitution and a range of functional groups.
