Preparation of 2-alkenylperhydro-1,3-benzoxazines and application for 2-isoxazolines synthesis
摘要:
Various 2-substituted-N-benzyl-4,4,7-trimethyl-trans-octahydro-1,3-benzoxazines 2 were prepared from the condensation of (-)-8-benzylaminomenthol 1 derived from (+)-pulegone, with acrolein, crotonaldehyde, cinnamaldehyde, 2(E)-N,N-diisopropyl-4-oxobut-2-enamide, ethyl (2E)-4-oxobut-2-enoate, and 2-furaldehyde in 71-96% yield. The 1,3-dipolar cycloaddition with aceto- and benzonitrile oxide gave the corresponding 2-isoxazoline cycloadducts. The origin of the stereoselectivity (4'S, 5'S-cycloadducts up to 64% de) arises from the cycloaddition of the dipole to the top of the Re,Re-alkene face of dipolarophile 2. (C) 2009 Elsevier Ltd. All rights reserved.
[3]Dendralene Synthesis: Rhodium(III)-Catalyzed Alkenyl CH Activation and Coupling Reaction with Allenyl Carbinol Carbonate
作者:Honggen Wang、Bernhard Beiring、Da-Gang Yu、Karl D. Collins、Frank Glorius
DOI:10.1002/anie.201306754
日期:2013.11.18
[3]DendrAl(l)ene! A new synthesis of [3]dendralenes is based on a RhIII‐catalyzed alkenyl CH activation and coupling reaction with allenyl carbinol carbonates (see scheme; DG=directing group). A variety of [3]dendralenes with diverse substitution patterns are accessible with good efficiency. The reaction is highly stereoselective and compatible with different directing groups and numerous functional