- Tf2O/TTBP (2,4,6-Tri-tert-butylpyrimidine): An Alternative Amide Activation System for the Direct Transformations of Both Tertiary and Secondary Amides
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Ten types of Tf2O/TTBP-mediated amide transformation reactions were investigated. The results showed that compared with pyridine derivatives 2,6-di-tert-butyl-4-methylpyridine (DTBMP) and 2-fluoropyridine (2-F-Pyr.), TTBP can serve as an alternative amide activation system for the direct transformation of both secondary and tertiary amides. For most surveyed examples, higher or comparable yields were generally obtained. In addition, Tf2O/TTBP combination was used to promote the condensation reactions of 2-(tert-butyldimethylsilyloxy)furan (TBSOF) with both tertiary and secondary amides, the one-pot reductive Bischler-Napieralski-type reaction of tertiary lactams, and Movassaghi and Hill's modern version of the Bischler-Napieralski reaction. The value of the Tf2O/TTBP-based methodology was further demonstrated by the concise and high-yielding syntheses of several natural products.
- He, Qian,Ye, Jian-Liang,Xu, Fang-Fang,Geng, Hui,Chen, Ting-Ting,Chen, Hang,Huang, Pei-Qiang
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- General one-pot reductive gem-bis-alkylation of tertiary lactams/amides: Rapid construction of 1-azaspirocycles and formal total synthesis of (±)-cephalotaxine
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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
- Xiao, Kai-Jiong,Luo, Jie-Min,Xia, Xiao-Er,Wang, Yu,Huang, Pei-Qiang
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p. 13075 - 13086
(2013/10/01)
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- Direct, one-pot sequential reductive alkylation of lactams/amides with grignard and Organolithium reagents through lactam/amide activation
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(Figure Presented) Be dazzled by the sequence: The first efficient and general one-pot method for the reductive bisalkylation of lactams/ amides with Grignard and organolithium reagents has been developed (see scheme; DTBMP = 2,6-di-tert-butyl-4methylpyridine, Tf=trifluoromethanesulfonyl).
- Xiao, Kai-Jiong,Luo, Jie-Min,Ye, Ke-Yin,Wang, Yu,Huang, Pei-Qiang
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supporting information; experimental part
p. 3037 - 3040
(2010/07/05)
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- An efficient method to convert lactams and amides into 2,2-dialkylated amines
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(Chemical Equation Presented) A practical method for the synthesis of gem-2,2-disubstituted tertiary amines from the corresponding lactams (or amides) is reported. It is based on the reaction of thioiminium ions, easily prepared from lactams and amides wi
- Agosti, Alessandro,Britto, Sebastian,Renaud, Philippe
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supporting information; experimental part
p. 1417 - 1420
(2009/04/12)
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- Ring-closing metathesis of 2,2-diallyl derivatives of pyrrolidine and piperidine: a route to azaspiroheterocyclic structures
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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
- Bespalova, N. B.,Shuvalova, O. V.,Zaikin, V. G.,Borisov, R. S.,Pastukhov, F. V.,Bubnov, Yu. N.
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p. 645 - 648
(2007/10/03)
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