Regioselective functionalization. .beta. Substituent effects on the regioselectivity of Baeyer-Villiger oxidations of 3-substituted 2-azabicyclo[2.2.2]octan-5-ones (isoquinuclidin-5-ones)
Regioselective functionalization. .beta. Substituent effects on the regioselectivity of Baeyer-Villiger oxidations of 3-substituted 2-azabicyclo[2.2.2]octan-5-ones (isoquinuclidin-5-ones)
复制标题
DOI：
10.1021/jo00148a002
复制
发表时间：
1982-12
影响因子：
3.6
通讯作者：
G. Krow;C. A. Johnson;J. Guare;D. Kubrak;Kenneth J. Henz;D. Shaw;S. Szczepanski;J. T. Carey
中科院分区：
文献类型：
--
作者：
G. Krow;C. A. Johnson;J. Guare;D. Kubrak;Kenneth J. Henz;D. Shaw;S. Szczepanski;J. T. Carey
N-烷氧羰基-2-氮杂双环[2.2. 2]已发现辛-5-酮1作为3-位取代基的特性和立体化学以及过酸氧化剂的选择的函数而显著变化。用过乙酸，从酮Ib（R ′ = exo-Me，62%BH）、Ie（R ′ = exo-CH 2 OCOPh，84%BH（TLC））和Ig（R= endo-COOMe，66%BH（TLC））获得主要桥头（BH）-迁移的内酯2，并且仅从酮Ia（R ′ = H）、Ic（R ′ = exo-Ph）和Id（R ′ = exo-COOMe）获得桥头迁移。酮If（R= endo-Me）不能被过氧乙酸氧化。当间氯过苯甲酸被用作氧化剂时，在每种情况下都得到了更大量的亚甲基迁移内酯4。对于Id（R '= exo-COOMe，18%BH（TLC））和lg（R= endo-COOMe，38%BH（TLC）），亚甲基迁移内酯4是主要的内酯，尤其是Id（R'= exo-COOMe），在过氧乙酸作用下2d时100%的桥头迁移内酯，而在间氯过氧苯甲酸作用下4d时82%的桥头迁移内酯。当过氧乙酸用作氧化剂时，酮1的迁移倾向与酮1的羰基碳的13 C NMR位移不相关，但Id（R '= exo-COOMe）和lg（R= endo-COOMe）中酮羰基碳的共振的高场位移确实与以间氯过苯甲酸作为氧化剂的亚甲基迁移的偏好相关。
The regioselectivity of the Baeyer-Villager oxidation of lV-carboalkoxy-2-azabicyclo [2.2. 2] octan-5-ones 1 has been found to vary markedly as a function of the identity and stereochemistry of the substituent at the 3-position and the choice of peracid oxidant. With peracetic acid predominantly bridgehead (BH)-migrated lactones 2 were obtained from the ketones lb (R'= exo-Me, 62% BH), le (R'= exo-CH2OCOPh, 84% BH (TLC), and lg (R= endo-COOMe, 66% BH (TLC) and exclusively bridgehead migration from the ketones la (R'=H), lc (R'= exo-Ph), and Id (R'= exo-COOMe). The ketone If (R= endo-Me) failed to undergo oxidationwith peracetic acid. When m-chloroperbenzoic acid was used as the oxidant, greater amounts of methylene-migratedlactones 4 were obtained in every case examined. For ketones Id (R'= exo-COOMe, 18% BH (TLC), and lg (R= endo-COOMe, 38% BH (TLC), methylene-migrated lactones 4 were the predominant lactones found. The change in migratory preference was especially notable with Id (R'= exo-COOMe), which afforded 100% bridgeheadmigrated lactone 2d with peracetic acid but 82% methylene-migrated lactone 4d with m-chloroperbenzoic acid. Migratory aptitudes for ketones 1 could not be correlated with 13C NMR shifts of the carbonyl carbons of the ketones 1 when peracetic acid was used as the oxidant, but upfield shifts for the resonances of the ketone carbonyl carbons in Id (R'= exo-COOMe) and lg (R= endo-COOMe) did correlate with a preference for methylene migration with m-chloroperbenzoicacid as the oxidant.