457605-92-4Relevant articles and documents
General one-pot reductive gem-bis-alkylation of tertiary lactams/amides: Rapid construction of 1-azaspirocycles and formal total synthesis of (±)-cephalotaxine
Xiao, Kai-Jiong,Luo, Jie-Min,Xia, Xiao-Er,Wang, Yu,Huang, Pei-Qiang
, p. 13075 - 13086 (2013/10/01)
Amides are a class of highly stable and readily available compounds. The amide functional group constitutes a class of powerful directing/activating and protecting group for C-C bond formation. Tertiary tert-alkylamine, including 1-azaspirocycle is a key structural feature found in many bioactive natural products and pharmaceuticals. The transformation of amides into tert-alkylamines generally requires several steps. In this paper, we report the full details of the first general method for the direct transformation of tertiary lactams/amides into tert-alkylamines. The method is based on in situ activation of amide with triflic anhydride/2,6-di-tert-butyl-4-methylpyridine (DTBMP), followed by successive addition of two organometallic reagents of the same or different kinds to form two C-C bonds. Both alkyl and functionalized organometallic reagents and enolates can be used as the nucleophiles. The method displayed excellent 1,2- and good 1,3-asymmetric induction. Construction of 1-azaspirocycles from lactams required only two steps or even one-step by direct spiroannelation of lactams. The power of the method was demonstrated by a concise formal total synthesis of racemic cephalotaxine. Four bonds in one pot! Cleavage of two bonds of an amide carbonyl group and replacement by two new C-C bonds can be achieved in one pot under mild conditions by using amide activation with triflic anhydride (Tf2O). A concise formal total synthesis of racemic cephalotaxine has been accomplished by means of this methodology (see scheme; DTBMP=2,6-di-tert-butyl-4-methylpyridine). Copyright
Ring-closing metathesis of 2,2-diallyl derivatives of pyrrolidine and piperidine: a route to azaspiroheterocyclic structures
Bespalova, N. B.,Shuvalova, O. V.,Zaikin, V. G.,Borisov, R. S.,Pastukhov, F. V.,Bubnov, Yu. N.
, p. 645 - 648 (2007/10/03)
Transformations of 1-benzyl-2,2-di(2-propenyl)pyrrolidine and 1-benzyl-2,2-di(2-propenyl)piperidine into the corresponding 1-azaspiro[4.n]alkenes via ring-closing metathesis using accessible homogeneous catalytic systems WCl6-H2SiPh2, WOCl4-H2SiPh2, and R
