Absolute configuration of diterpenoid diacylglycerols from the Antarctic nudibranch Austrodoris kerguelenensis

The R absolute configuration at C-2' of the glyceryl moiety of the natural diterpenoid 1,3-glyceryl esters 1 and 2 has been established by applying the modified Mosher method. These esters have been isolated, together with the corresponding 1,2-derivatives (3 and 4), from different collections of the Antarctic dorid nudibranch Austrodoris kerguelenensis. Surprisingly, such a configuration is opposite to that of all marine terpenoid diacylglycerols so far reported. Compounds 1 and 3 are new natural products closely related to austrodorin 5, already described from the same species. (C) 1999 Elsevier Science Ltd. All rights reserved.