2 DIASTEREOISOMERS OF 1-(10-TRIFLUOROMETHYL-11,12-DIOXATETRACYCLO-[6.2.1.13,6.02,7]DODECA-4,9-DIEN-9-YL)ETHYL PHENYLACETATE, C21H19F3O4 - MEMBERS OF A SERIES OF ADDUCTS GENERATED BY REPEATED DIELS-ALDER CYCLOADDITION OF FURAN TO 5,5,5-TRIFLUOROPENT-3-YN-2-YL PHENYLACETATE

Both the tide bis adducts are anti joined, differing only in the enantiomeric form of the (phenylacetoxy)ethyl substituent relative to the main ring system. hi each case, a CF3 fluorine nearly eclipses the double bond [F-C-C=C; isomer (1), 5.9 (7); isomer (2), 10 (2)-degrees], thereby permitting the adjacent substituent to stagger and the bulky phenylacetoxy group to project away [C=C-C-O; isomer (1), -161.6 (4); isomer (2), 157 (1)-degrees]. Changes in steric congestion introduced by the structural differences are relatively minor, allowing similar quantities of both compounds to be produced [isomer (1), 10; isomer (2), 8%].