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Tuesday, August 25 • 3:40pm - 4:00pm
[0107] Practical Synthesis of N-Substituted Cyanamides as N-C-N Building Blocks for Heterocycle Synthesis

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A variety of carboxamidoximes (2), prepared from carbonitriles with NH2OH, could react with benzenesulfonyl chlorides (TsCl or o-NsCl) and DIPEA to form N-substituted cyanamides (3) in very good yields. The benzenesulfonyl chlorides promoted Tiemann rearrangement of carboxamidoximes (2) is readily amenable for the synthesis of a wide variety of cyanamide derivatives in multi-gram scales from carbonitriles.1 Acidic hydrolysis of the N-substituted cyanamides (3) afforded the corresponding N-monosubstituted ureas (4) in good yields. The preparation of the N-monosubstituted ureas (4) could also be accomplished in a one-pot fashion effectively from carbonitriles (2) with comparable yields.2 N-Alkyl-N’-arylguanidines (5) could be obtained from the reaction of N-arylcyanamides (3) with various primary and secondary alkylamines, under the catalysis of CuI and Xantphos in DMF. This methodology provides a direct access to versatile N,N’-disubstituted guanidine derivatives (5) from previously described N-arylcyanamides (3).3 The application of N-substituted cyanamides (3) toward the synthesis of various heterocycles, including benzimidazoles, benzoxazoles, and quinazolinones, has also been demonstrated.

ST Lecturers
avatar for Tun-Cheng Chien

Tun-Cheng Chien

Professor, National Taiwan Normal University

Tuesday August 25, 2015 3:40pm - 4:00pm PDT
UCEN Flying A