Alkynylindium reagents

Anomeric acetates 104 have been also used as electrophiles toward alkynylindium reagents 105 under Barbier conditions. Good yields and 1,2-cA-stereoselectivities were observed during the reaction (Scheme 36). The alkynylation was applied to the synthesis of an a-(l —>6)-C -disaccharide (110) analogue of methyl isomaltoside.108... 

Owing to their pronounced reactivity, alkynylindium reagents typically require short reaction times. The possibility of a stoichiometry-controUed sequential one-pot cross-coupling to 3,4-dichloromaleimides under Pd catalysis has been demonstrated [362]. A distinct chemoselectivity of triorganoindium reagents has been observed favoring replacement of bromo over chloro functionahties in 2,5-dihalopyrimidines [360]. 

Table 9.24 Representative examples of other alkynylindium reagents in cross-couplings.

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