Propargylation carbonyls, with indium compounds

The coupling reaction of a-keto esters with allyl, propargyl, and allenyl halides using indium metal in aqueous solvents affords a-hydroxy-y,<5-unsaturated esters (Equation (28)).197,198 1,3-Dicarbonyl compounds undergo efficient carbonyl allylation reactions in an aqueous medium through a Barbier-type reaction (Equation (29)). The reaction is general and a variety of 1,3-dicarbonyls has been alkylated using allyl bromide or allyl chloride in conjunction with indium.199... 

By the action of indium, various allylic or propargylic dihalo compounds can be converted to the respective dianion equivalents. In some cases, the reaction with electrophiles proceeds stepwise, whereas in other cases novel diindium reagents are involved. Via an indium-mediated Barbier-type reaction in an aqueous medium, carbonyl compounds react with a trimethylenemethane dianion equivalent to give the corresponding diols (Equation (39)).218... 

Allylation and propargylation of carbonyl compounds have been surveyed [5]. This section focuses on regio- and stereochemical aspects of the carbonyl allylation reactions in organic and aqueous media. Allylation of carbonyl compounds also proceeds under solvent-free conditions [10] or in liquid carbon dioxide [11]. Allylation with a catalytic amount of indium (0.01-0.1 equiv.) in combination with manganese and chlorotrimethylsilane has been reported [12]. Allylindium reagents have successfully been applied to syntheses of several natural products [13]. 

Propargylation. An approach to epoxyalkynes involves indium-mediated reaction of a-chloropropargyl sulfides with carbonyl compounds. Interestingly, opposite stereoselectivity is shown by a reaction using In and InCl,. 

AUylation and propargylation reactions. In the presence of the (Ph3P)4Pd catalyst, indium(I) iodide form organoindium(III) reagents with allylic halides and propargylic mesylates that react with carbonyl compounds in various solvents. 

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