Isolated 2 yield0 (%) Lewis acid 1 Entry (equiv.) R' R2 R3 3 4 ... 1 2 3 4 5 6 7 8 ... H H - 87 H H 83 52 H H - 23 Me H 56 - H Me 55 - H H 84 78 H H 65 78 H H - 60 ... 0 Work-up procedures A and/or B were used, except where otherwise indicated. b Determined by 1H NMR using p-xylene as an internal standard. ... Published on 01 January 1996. Downloaded by google on 16/04/2016 21:05:38. ... View Article Online / Journal Homepage / Table of Contents ...