有機スズヒドリドの機能制御に基づく官能基,立体および位置選択的還元反応

概要

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Novel types of tin hydrides were developed by the introduction of a halogen substituent or a ligand on the tin atom. These modified tin hydrides achieved chemoselective reduction between carbonyl groups and other functionalities such as organic halides, epoxides, imines and enones. In the reaction with epoxy ketones, two types of tin hydrides Bu3SnH-Bu4NF and Bu2SnFH-HMPA systems reduced only the carbonyl moieties with high syn- and anti-selectivities, respectively. Whereas, when Bu2SnIH -HMPA was used, the reduction of epoxide groups took place to give 3-hydroxy ketone, where the carbonyl groups were tolerated. The high nucleophilicity of Sn-I bond toward epoxides is responsible for the selectivity. Tin chloride hydride complex, Bu2SnClH-HMPA was revealed to reduce imines over carbonyl groups. In the reduction of conjugated enone, Bu2SnFH afforded 1, 2-reduction predominantly to give allylic alcohol. On the other hand, Bu2SnIH promoted the selective 1, 4-reduction of enones even in the presence of aldehydes. When a mixture of an enone and PhCHO was treated with Bu2SnIH, the first resulting tin enolate subsequently reacted with co-existent PhCHO to give an aldol product.
社団法人有機合成化学協会の論文
1998-04-01