4－戊烯醛类化合物的铑催化不对称环化反应中烷基取代基的影响

Effect of the Alkyl Substituents on the Rh Catalyzed Cyclization of 4 Penten 1 als

在４－戊烯醛类化合物的铑催化环化反应中，当连结在双键上的烷基取代基是季碳原子时，如ｔ－Ｂｕ、ＤＭＰ、Ｍｃｘ，得到的对映选择性最高（＞９９％ｅ．ｅ．）。烷基取代基对反应的影响，依据对映选择性降低的顺序是季碳原子＞仲。

Effect of the alkyl substituents on the cyclization of 4 penten 1 als by [Rh(BINAP)]ClO 4 was investigated. Highly enantioselective fashion(>99% e.e.) was achieved when alkyl substituent is a quaternary cabon such as t Bu, 1,1 dimethylpropyl, and 1 methyl 1 cyclohexyl. The enantioselectivity in cyclization decreased when carbon adjacent to the double bond is primary secondary or tertiary. The order of decrease is quaternary carbon>secondary and primary carbn>tertiary carbon.