Tf<sub>2</sub>O/TTBP (2,4,6-Tri-<i>tert</i>-butylpyrimidine): An Alternative Amide Activation System for the Direct Transformations of Both Tertiary and Secondary Amides
Qian He, Jian‐Liang Ye, Fangfang Xu, Hui Geng, Tingting Chen, Hang Chen, Pei‐Qiang Huang
Abstract
Ten types of Tf 2 O/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, Tf 2 O/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 Tf 2 O/TTBP-based methodology was further demonstrated by the concise and high-yielding syntheses of several natural products.