One-step spiroannulation using 1,2-bis(methylene)cycloalkane-magnesium reagents
摘要:
A one-step method for the synthesis of a wide variety of spirocyclic systems has been developed based on the reactions of bis-electrophiles with a series of new 1,3-diene-magnesium reagents, the magnesium complexes of 1,2-bis(methylene)cycloalkanes. The direct metalation of 1,2-bis(methylene)cycloalkanes with highly reactive magnesium in THF at ambient temperature generates the corresponding diene-magnesium reagents in high yields. Reactions of the diene-magnesium reagents with 1,n-dibromoalkanes produce a large number of spirocarbocycles containing an exocyclic double bond. The ring sizes of the accessible spiro compounds can be any combinations of four- to seven-membered rings. In most cases, the initially alkylated intermediates can be trapped by protonation, giving the corresponding bromo olefins. Significantly, treatment of the diene-magnesium reagents with bromoalkyl nitriles leads to a one-step synthesis of keto-functionalized spirocycles. The initial adduct is believed to be a Grignard reagent containing a cyano group. When a bromo nitrile containing a cyclic moiety is used as the bis-electrophile, the approach provides a direct access to dispiroenones.
Organobis(cuprates): a new class of reagents and method for spiroannelation
作者:Paul A. Wender、Alan W. White
DOI:10.1021/ja00215a035
日期:1988.3
Reaction d'organobiscuprates avec des halogeno-3 cyclohexene- et -cyclopentene-2ones: obtention de cyclohexanones et cyclopentanones spiranes en position 3
反应 d'organobiscuprates avec deshalo-3 cyclohexene-et-cyclopentene-2ones: 获得环己酮和环戊酮螺环在位置 3
The magnesium complexes of 1,2-dimethylenecycloalkanes: a new method for a one-step spiroannelation
作者:Heping Xiong、Reuben D. Rieke
DOI:10.1016/s0040-4039(00)92361-x
日期:1991.9
Reactions of new dienemagnesium reagents prepared from highly reactive magnesium and 1,2-dimethylenecycloalkanes with 1,n-dibromoalkanes and bromoalkylnitriles provide a one-step method for the synthesis of commonly encountered spirocyclic systems.
SPIROANNELATION VIA ORGANOBIS(CUPRATES): 9,9-DIMETHYLSPIRO[4.5]DECAN-7-ONE
作者:Wender, Paul A.、White, Alan W.、McDonald, Frank E.
DOI:10.15227/orgsyn.070.0204
日期:——
WENDER, PAUL A.;WHITE, ALAN W., J. AMER. CHEM. SOC., 110,(1988) N 7, 2218-2223