| Abstract
| - Comprehensive studies were carried out on efficient In- or In(I)-based diastereoselective Reformatsky-type reactions of simple ketones, α-alkoxy ketones, and β-keto esters. High anti selectivitywas established in the addition of the branched α-halo ester derivatives to simple ketones usingindium metal under THF-refluxing conditions. The stereochemistry undoubtedly indicated thatthe involvement of a cyclic transition state, formed from the ketone and stereochemically preferredtransient E-enolate derived from the branched α-halo ester. Next, with the view of tailoring highdegree of stereoselection, the concept of chelation-controlled addition of indium enolates wasenvisioned. In this line, marvelously syn selective additions to α-alkoxy ketones and β-keto esterswere established. Interestingly, these diastereoselective additions to α-alkoxy ketones and β-ketoesters require either In(I)X or In−InCl3 systems in toluene under ultrasonication, while very poorefficiency and diastereoselectivity were obtained using indium metal or THF as solvent. Thestereochemistry of key products was unambiguously determined by the single-crystal X-ray structureanalyses. On the basis of the observed astonishing diastereoselectivities due to strong chelationplausibly, a low-valent RIn(I)-type transient spices could be projected as very reactive spices inthe Reformatsky-type reactions.
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