The unexpected rearrangement of N-allyl-2-phenyl-4,5-dihydrooxazole-4-carboxamides in the presence of LiHMDS has been found. The key features are: (1) the net reaction consisted of 1,3-migration of the N-allyl group, (2) the rearrangement produced a congested aza-quaternary carbon center, (3) both cyclic and acyclic substrates underwent the unexpected rearrangement to afford products in moderate to
Modular Synthesis of 1,2-Diamine Derivatives by Palladium-Catalyzed Aerobic Oxidative Cyclization of Allylic Sulfamides
作者:Richard I. McDonald、Shannon S. Stahl
DOI:10.1002/anie.200906342
日期:——
Allylic sulfamides undergo aerobic oxidativecyclization at room temperature, mediated by a Pd(O2CCF3)2/DMSO catalyst system in tetrahydrofuran. The cyclic sulfamide products are readily converted into 1,2‐diamines, and substrates derived from chiral allylic amines cyclize with very high diastereoselectivity.
A New Synthesis of Ciliapterin and Dictyopterin. Ene Reactions of (Alkenylamino)-nitroso-pyrimidines
作者:Fang-Li Zhang、Andrea Vasella
DOI:10.1002/hlca.200890255
日期:2008.12
A comparison of the reactivity of (acylamino)-nitroso-pyrimidines 1 and the alkenylamino analogue 17 in intramolecular enereactions showed the considerably lower reactivity of 17, leading to the pteridine 18. Pteridin-7-one 11 resulting from 1 (R1=OBn, R2=Me) was transformed into 4-(benzyloxy)-6-[(E)-prop-1-enyl]pteridin-2-amine (13) by O-triflation, followed by reduction with LiBHEt3, while the 4-MeO