ORGANOMETALLIC RING-OPENING REACTIONS OF N-ACYL AND N-ALKOXYCARBONYL LACTAMS - SYNTHESIS OF CYCLIC IMINES
ORGANOMETALLIC RING-OPENING REACTIONS OF N-ACYL AND N-ALKOXYCARBONYL LACTAMS - SYNTHESIS OF CYCLIC IMINES
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DOI：
10.1021/jo00262a048
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发表时间：
1989-01-06
影响因子：
3.6
通讯作者：
UMANIRONCHI, A
中科院分区：
文献类型：
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作者：
GIOVANNINI, A;SAVOIA, D;UMANIRONCHI, A
用己基溴化镁和苯基溴化镁与n -酰基和j -烷氧羰基内酰胺在78℃的四氢呋喃中反应，确定了影响区域选择性的因素。/ v -戊酰7-内酰胺与两种格氏试剂均发生开环反应，而n -苯甲酰7-内酰胺仅与苯溴化镁发生完全选择性反应。IV-Cbz 7-内酰胺优先与外环羰基反应，特别是与己基溴化镁反应。boc五元八元内酰胺通过开环反应生成iv - boc - v-氨基酮，但随着环尺寸的增大，效率略有降低。然后- boc -a b> -氨基酮与三氟乙酸脱保护，容易得到相应的五至七元环亚胺。利用更容易获得的吡啶锂试剂，而不是相应的格氏试剂，通过改进的路线制备了含环亚胺部分的吡啶生物碱。
The reactions of hexyl-and phenylmagnesium bromides with N-acyl and jV-alkoxycarbonyl lactams in tet-rahydrofuran at-78 C have been performed to determine the factors affecting the regioselectivity./V-Pivaloyl 7-and-lactams undergo the ring-opening reactions with both Grignard reagents, whereas on the N-benzoyl 7-lactam a complete selectivity is achieved only with phenylmagnesium bromide. The IV-Cbz 7-and-lactams preferentially react at the exocyclic carbonyl group, especially with hexylmagnesium bromide. The-Boc fiveto eight-membered lactams undergo the ring-opening reaction to give IV-Boc-tv-amino ketones, although the efficiency slightly decreases by increasing the ring size. The deprotection of theN-Boc-a>-amino ketones with trifluoroacetic acid easily affords the corresponding five-to seven-membered cyclic imines. Pyridine alkaloids containing the cyclic imine moiety have been prepared by a modified route, exploiting the more easily available pyridyllithium reagents, instead of the corresponding Grignard reagents.