An unusual rearrangement of the thujane skeleton under free-radical conditions: Synthesis of thioacetates and thiols derivatives of (-)-sabinene

Photochemical acetylthiolation of (-)-sabinene 1 afforded 10-acetylthiothujane 2 and an unexpected cyclopentenyl methyl thioacetate 3 in moderate yield (24%). Hydride reduction of these two latter compounds gave two monoterpenoid thiols ( 2a and 3a ) in excellent yield (95%). The odour of the major sulfur-containing compounds 2 and 2a was respectively described as being typically anisic and as reminiscent of cooked leek. Structural determination of these derivatives was achieved by one- and two-dimensional NMR spectroscopy.