Trachyopsis aplysinoides

The first sesquiterpene thiocyanate to be isolated from a marine sponge was (15, 45, 65, 7/ )-4-thiocyanato-9-cadinene (253) from Trachyopsis aplysinoides. The structures of this compound and of an isothiocyanate with a new carbon skeleton (254), were determined by X-ray analysis and two additional isothiocyanates (255-256) were identified [258]. Isothiocyanate 254 was synthesised using an oxidative radical cyclisation reaction as a key step [259]. 

The structure of 5-isothiocyanatopupukeanane (257), a sesquiterpene isothiocyanate from an Axinyssa species from Guam, was determined by X-ray analysis [260]. Two isomeric sesquiterpene thiocyanates, 2-thiocyanatoneopupukeanane (258) and 4-thiocyanatoneopupukeanane (259) were isolated from an unidentified sponge from Pohnpei and from Phycopsis terpnis from Okinawa [261]. A sample of Axinyssa (= Trachyopsis) aplysinoides from Palau yielded a rare thiocyanate, 2-thiocyanatopupukeanane (260), while two specimens from Pohnpei yielded 13-isothiocyanatocubebane (261), 1-isothiocyanatoaromadendrane (262) and 2-thiocyanatoneopupukeanane (258) [262]. This last compound had previously been assigned different stereochemistry at C2 [261]. (-)-4-Thiocyanatoneopupukeanane has been synthesised in an enantiospecific manner (259) [263]. Both enantiomers of 2-thiocyanatoneopupukeanane (258) have been synthesised from (7 )-carvone [264]. 

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