Asymmetric synthesis of the oxabicyclic products is possible through utilization of rhodium(II) (S)-N-(tert-butylbenzene)sulfonylprolinate as catalyst or by using (S)-lactate or (R)-pantolactone as chiral auxiliaries on the carbenoid. The highest yields (69−95%) and asymmetric induction (82−95% de) were obtained using 3-siloxy-2-diazo-3-butenoate derivatives as the vinylcarbenoid precursors.
在
呋喃的存在下,
羧酸铑 (II) 催化
乙烯基重氮甲烷的分解导致一般合成氧杂双环 [3.2.1] octa-2,6-二烯衍
生物。这些氧双环产品是有机合成中的通用中间体。[3 + 4] 环化的机制被认为是串联
环丙烷化/Cope 重排。这种机制与在这些 [3 + 4] 环中观察到的出色的区域和立体控制是一致的。通过使用
铑(II)(S)-N-(
叔丁基苯)磺酰基脯
氨酸盐作为催化剂或使用(S)-
乳酸盐或(R)-泛内酯作为类卡宾的手性助剂,可以不对称合成氧杂双环产物。