I. Kitagawa, K. Kitazawa, L. Yosioka
1972
Citations
0
Influential Citations
18
Citations
Journal
Tetrahedron
Abstract
Abstract Being interested in the photochemical reactions which are potentially applied in the biogenetic-type chemical derivations of natural products, the appropriate photochemical means have been sought to produce the 11α,12α-epoxy-13β,28-lactone moiety in the oleanane skeleton, which is one of the unique functions of eupteleogenin ( 2 ). Photooxidation of oleanolic acid ( 6a ) in acidic medium has been undertaken and desired 11α,12α-epoxy-oleanolic lactone ( 12a ) obtained. Erythrodiol ( 8a ) has been submitted to photooxidation and the 11α,12α-epoxy-13β,28-oxide moiety ( 24a ) introduced along with skeletal rearrangement affording the 11α,12α-epoxy-taraxerene derivative ( 25a ). During photooxidation of 8a , it has been noticed that 11ξ-hydroxy-olean-12-ene derivatives ( 28, 42 ) are fairly labile, allowing the trans-formation of dihydropriverogenin A( 10a ) into the thermodynamically less favored isomer priverogenin B( 9 ).