Regio- and diastereoselective ene reaction of 4-phenyl-1,2,4-triazoline-3,5-dione with chiral allylic alcohols and their derivatives

Chiral allylic alcohols la-e reacted with 4-phenyl-1,2,4-triazoline-3,5-dio ne (PTAD) in CH2Cl2 to produce 3-amino-1-alken-4-ols 2 and 3 in 78-89% yiel ds, with 68-90% diastereomeric excess (de) in favor of the three isomer. Ch iral allylic ethers If,g and acetates Ih,i gave similar yields but lower de (34-66%). Reaction of allylic alcohols 6a-e with PTAD in CH2Cl2 produced 1 ,3-regioisomers 7 and 8 exclusively in 33-65% yields without apparent diast ereoselectivity, except when R-1 was a Bu-t group, in which case only syn p roduct 7 was formed. However, when 6a or 6c was subjected to reaction with PTAD in a polar solvent, up to 88% de was observed. Reaction of allylic eth ers 6f,g and acetates 6h,i with PTAD in CH2Cl2 also produced 7 and 8 exclus ively with improved yields (56-96%) and diastereoselectivity (50-100% de in favor of the syn isomer).