27723-50-8Relevant academic research and scientific papers
One-step Spiroannulation Using 1,2-Bis(methylene)cycloalkane-Magnesium Reagents
Rieke, Reuben D.,Xiong, Heping
, p. 6560 - 6565 (2007/10/02)
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 temperatures 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.
THE MAGNESIUM COMPLEXES OF 1,2-DIMETHYLENECYCLOALKANES: A NEW METHOD FOR A ONE-STEP SPIROANNELATION
Xiong, Heping,Rieke, Reuben D.
, p. 5269 - 5272 (2007/10/02)
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.
