Helvetica Chimica Acta

Steric carbonyl protection metalation and cleavage of highly hindered ureas. Preliminary communication

T Hassel, D Seebach

文献索引：Hassel,T.; Seebach,D. Helvetica Chimica Acta, 1978 , vol. 61, p. 2237 - 2240

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被引用次数: 22

摘要

Abstract Ureas of type 3 with sterically protected carbonyl groups such as 4a-7a are prepared by successively adding 2 equivalents of a highly substituted sec. amine and an excess of dimethylamine to benzene or toluene solutions of phosgene. The piperidine derivatives 6a and 7a are metalated in high yields to 6b and 7b, respectively, with sec.- butyllithium/TMEDA in THF at 0 [see derivatives 6, 7,(ci) in Table 1]. Methods of cleaving ...