B. Koppenhoefer et al., SUBSTITUTION WITH SULFUR AT THE STERICALLY HINDERED NEOPENTYL POSITION - PREPARATION OF 9-MERCAPTOCAMPHOR AND 9,10-EPITHIOCAMPHOR, Synthesis, (5), 1997, pp. 515
A variety of methods for S(N)2 substitution at sterically hindered 9-b
romocamphor (2) was tested for the preparation of 9-mercaptocamphor (1
), a fragrant compound with a roasty note reminiscent of onion. All re
agents failed, with the notable exception of potassium thioacetate in
N-methylpyrrolidone (for 3 days at 180 degrees C). The peculiar reacti
vity pattern of both neopentyl-type 2 and 9,10-dibromocamphor (9) invo
lves surprisingly smooth substitution reactions where strain is releas
ed. Thus, 9 was transformed into tricyclic 9,10-epithiocamphor 12, as
established by X-ray analysis.