Diastereoselective Manipulations of Bicyclo[<i>m</i>.1.0]alkane Derivatives. 4. Reactions of Nucleophiles with Bicyclo[<i>m</i>.1.0]alk-3-en-2-ones
作者:Eugene A. Mash、Timothy M. Gregg、James A. Baron
DOI:10.1021/jo971359h
日期:1997.11.1
of lithium diorganocuprates were highly diastereoselective for the 8- and 12-membered enones but were not diastereoselective for the 15-membered enone. All reactions were chemically efficient. The diastereoselectivities observed for 1,2-additions, which are thought to involve early transition states, can be rationalized by consideration of the low-energy conformations of each cyclopropyl enone. The
制备具有8、12和15元环的对映异构体富集的双环[m.1.0] alk-3-en-2-one,并使其添加亲核试剂。对所有检查的环丙基烯酮,1,2-正丁基锂的加成对映体选择性高。(Z)-双环[6.1.0] non-3-en-2-one和(E)-双环[13.1.0] hexadec-3-en-2-one与二甲基氧os甲基化的反应具有很高的非对映选择性,而(E)-双环[10.1.0] tridec-3-en-2-one与该试剂的非对映选择性。相比之下,添加1,4-二有机铜锂对8和12元烯酮具有非对映选择性,而对15元烯酮则非对映选择性。所有反应在化学上都是有效的。对于1,2-加成观察到的非对映选择性,被认为与早期过渡态有关,可以通过考虑每个环丙基烯酮的低能构象来合理化。在1,4-加成中观察到的非对映选择性可能涉及后期跃迁状态,与这些烯酮的最低能量构象并不简单相关。