Vinylogous urea substrates

Vinylogous urea substrates have also been used in the aza-annulation reaction to form 6-lactam products. This process was illustrated by the condensation of fi-keto amide 366 followed by aza-annulation with acryloyl chloride to give 367 (eq. 75).57-59 Catalytic reduction of the tetrasubstituted double bond led to stereoselective formation of 368. The products formed in this reaction were fi-enamino peptide units, and this chemistry can be extended to the preparation of tri-and tetrapeptide analogs. 

Additional examples of the DMP-mediated oxidations of nitrogen substrates include the synthesis of 2-substituted benzothiazoles 903 via oxidative cyclization of thioanilides 902 [445] and the synthesis of imldes (e.g., 904), N-acyl vinylogous carbamates and ureas and nitriles by the oxidation of amides and amines with DMP (Scheme 3.362) [1292],... 

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