Organocopper reagents coupling

All types of organocopper reagents couple readily with acid halides (Table XI), affording an alternative synthesis of ketones. Posner and... 

Halogens a to carbonyl groups can be successfully coupled using organocopper reagents. For example, 3,9-dibromocamphor is selectively arylated a to the carbonyl. 

One example for the reaction of a 229-type copper reagent is shown in Equation (128). Neopentyl-substituted organocopper reagent 230, which bears aldehyde, is generated followed by treatment with acetyl chloride to provide coupling product 231 in 70% yield. Application of this method to the selective functionalization of polyhalogenated aromatics was also reported.497... 

Propanol, 1,3-bis(methylthio)-, 54, 19 Propargyl bromide, coupling with an organocopper reagent, 50, 98... 

Buynak et al. reported the synthesis of representative 7-vinylidenecephalosporine derivatives bearing an axial allene chirality (Scheme 4.5) [9]. A chiral allene 24 was prepared stereoselectively utilizing the reaction of an organocopper reagent with propargyl triflate 23, obtained by a diastereoselective ethynylation of the ketone 22 with ethynylmagnesium bromide. Terminally unsubstituted allene 26 was synthesized via bromination of the triflate 23 followed by reduction of the bromide 25 with a zinc-copper couple. 

Sn2 substitution using organocopper reagents is an efficient method for the synthesis of 3-substituted olefins. In the synthesis of farnesyl diphosphate analogues (43, 45) as potential inhibitors of the enzyme protein-farnesyl transferase, for example, organocopper methodology was compared with the Stifle reaction [33] and the Suzuki reaction [34], frequently used in the coupling of vinyl triflates with... 

Scheme 57 illustrates an example of this process coupling of the lithio reagent derived from vinyl stannane 237 with epoxide 242 leads to the C-disaccharide derivative 243 in good yield. A double transmetallation to give an organocopper reagent 244 can facilitate the C-glycosylation reaction with allyl halides [80] (Scheme 58). 

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