Photochemical cycloadditions in the prostaglandin series

Novel prostaglandin E2 derivatives from PGA2

“…Similarly, the 15-alcohol of the p-isomer 5b exhibited a much stronger negative CD curve ([e],,, -8555) (dioxane) than its a-counterpart 66 ([0lZ9, -4245) (dioxane). These findings are in agreement with previous studies which have shown that C-10,ll P cyclo-prostanoids display an intense negative Cotton effect in the 300 nm region (2).…”

“…A mixture of stereoisomeric cycloadducts (2a) ([a], +31° (CHCl,); v, , , (neat): 3450, 1740 cm-I, 6 (in CCl,, using TMS as a standard): 0.89 (t, 20-Me), 1.93 and 1.97 (s, OAc), 3.6 (s,C02Me),vinylic H)) was obtained in 87% yield. There is ample precedent for the photochemical cycloaddition to the Alo-double bond of PGA, under these conditions (2). No significant amount of any positional isomer, i.e., C-10'-acetoxy derivative, was found (3).…”

“…A number of modified prostaglandins have recently been obtained from naturally occumng PGA, (la) through chemical (1) and photochemical (2) transformations. In this communication a photochemical preparation from PGA, of new C-10 derivatives of PGE, not easily accessible by other routes is described.…”

Méthylène‐10,11‐ et méthyl‐11‐prostaglandine

“…Des photocycloadditions sklectives sur la double-liaison C(lO)-C(11) des PG-A, ont permis de priparer diffirentes prostaglandines bicycliques [5]. [8], pour les produits 5 ( [ @] , , , = +264 (CH,OH)) et 6 ( [ @] , , , = +500; [ @] , , , = +460 (CH,0H))8).…”