Page 271 - Advanced Organic Chemistry Part A - Structure and Mechanisms, 5th ed (2007) - Carey _ Sundberg

cis isomers are formed in ratio of about 15:1. When the unprotected alcohols 251
are used with the Crabtree catalyst, quite high selectivity for the trans isomer is
found. Explain these results. PROBLEMS

R R R
cat or CH OX
2
N CH 2 OX N CH OX N 2
2
3 3
3 3
CO 2 C(CH ) CO 2 C(CH ) CO C(CH )
3 3
cat = Ra Ni cat = (C H ) P.Pyr.Ir(COD)PF 6
6 11 3
R X = t-Butyldimethylsilyl X = H
>40:1
H
C 2 5 13:1
>40:1
Ph 15:1
16:1
CH O C 15:1
3
2