Asymmetric 1,3-Dipolar Cycloadditions of 2-Diazocyclohexane-1,3-diones and Alkyl Diazopyruvates
作者:Paul Müller、Sabrina Chappellet
DOI:10.1002/hlca.200590071
日期:2005.5
The 1,3-dipolar cycloaddition reactions of 2-diazocyclohexane-1,3-dione (7a; Table 1) and of alkyl diazopyruvates (11a–e; Table 3) to 2,3-dihydrofuran and other enol ethers have been investigated in the presence of chiral transition metal catalysts. With RhII catalysts, the cycloadditions were not enantioselective, but those catalyzed by [RuIICl2(1a)] and [RuIICl2(1b)] proceeded with enantioselectivities
已经研究了2-重氮环己烷-1,3-二酮(7a;表1)和重氮丙酮酸烷基酯(11a - e;表3)与2,3-二氢呋喃和其他烯醇醚的1,3-偶极环加成反应。手性过渡金属催化剂的存在。使用Rh II催化剂时,环加成不是对映选择性的,但是当[Ru II Cl 2(1a)]和[Ru II Cl 2(1b)]催化时,对映选择性分别高达58%ee和74%ee。重氮丙酮酸盐11被用作基底。当用[Ru(pybox)]催化剂分解时,苯基碘化鎓叶立德7c比相应的重氮前体7a(表2)以较低的产率和较差的产率产生加合物8a。这表明与相应的重氮前体相反,Ru II催化剂进行的内鎓盐分解不会导致Ru-卡宾络合物作为反应性中间体。我们的方法代表了这些类型底物的首次可重现,对映选择性的1,3-环加成。