A variety of methods for SN2 substitution at sterically hindered 9-bromocamphor (2) was tested for the preparation of 9-mercaptocamphor (1), a fragrant compound with a roasty note reminiscent of onion. All reagents failed, with the notable exception of potassium thioacetate in N-methylpyrrolidone (for 3 days at 180°C). The peculiar reactivity pattern of both neopentyl-type 2 and 9,10-dibromocamphor (9) involves surprisingly smooth substitution reactions where strain is released. Thus, 9 was transformed into tricyclic 9,10-epithiocamphor 12, as established by X-ray analysis.
对立体位阻较大的9-
溴卡姆
酮(2)进行SN2取代的方法进行了多种测试,以制备9-巯基卡姆
酮(1),这是一种具有类似洋葱的烘烤气息的香气化合物。所有试剂均未成功,唯一例外是使用
N-甲基吡咯烷中的
乙酸钾硫代
酯(在180°C下反应3天)。无论是
新戊烷型2还是9,10-二
溴卡姆
酮(9)的特殊反应性模式都涉及意外顺利的取代反应,其中释放了应变。因此,已通过X射线分析确认将9转化为
三环9,10-环
硫卡姆
酮12。