No abstract

Donor-acceptor cyclopropanes are useful building blocks for catalytic cycloaddition reactions with a range of electrophiles to give various cyclic products. In contrast, relatively few methods are available for the synthesis of homoallylic alcohols through coupling of vinylcyclopropanes (VCPs) with aldehydes, even with transition-metal catalysts. Here, we report that the hydrostannation of vinylcyclopropanes (VCPs) was effectively promoted by dibutyliodotin hydride (Bu2 SnIH). The resultant allylic tin compounds reacted easily with aldehydes. Furthermore, the use of Bu2 SnIH was effectively catalytic in the presence of hydrosilane as a hydride source, which established a coupling reaction of VCPs with aldehydes for the synthesis of homoallylic alcohols without the use of transition-metal catalysts. In contrast to conventional catalytic reactions of VCPs, the presented method allowed the use of several VCPs in addition to conventional donor-acceptor cyclopropanes.

In this study, the BuSnIH-catalyzed direct coupling of 1,3-dienes with aldehydes was developed. This reaction could be suitable for coupling without the use of transition-metal catalysts. Many types of aldehydes were applied to this reaction. The addition of MeOH promoted the catalytic cycle.

Indium Hydride Catalyzed Chemo-and Diastereoselective Reductive Aldol Reactions. -A combination of MePhSiH 2 and methanol in the presence of catalytic amounts of dibromoindium methoxide efficiently promotes the reductive aldol condensation of enone (I) with different functionalized keto-compounds. Br 2InH is proposed to be the active catalytic species. Moreover, reductive removal of the bromo substituent of product (V) allows a highly diastereoselective access to derivative (VIII) which is not accessible from acetophenone. -(IEKI, R.; MIYAMOTO, S.; TSUNOI, S.; SHIBATA*, I.; J. Organomet. Chem. 751 (2014) 471-474, http://dx.

Transition-Metal-Free Coupling Reaction of Vinylcyclopropanes with AldehydesCatalyzed by Tin Hydride. -Hydrostannation of vinylcyclopropanes (VCPs) followed by reaction with aldehydes gives access to homoallylic alcohols without the use of transition-metal catalysts. The hydrostannation reaction is catalytic in Bu 2SnHI provided the presence of hydrosilane as a hydride source. In contrast to established catalytic reactions of VCPs this protocol is not restricted to donor-acceptor cyclopropanes. -(IEKI, R.; KANI, Y.; TSUNOI, S.; SHIBATA*, I.; Chem. -Eur. J. 21 (2015) 16, 6295-6300, http://dx.