Carbonyl Propargylation and Allenylation with 2-Propynyl Mesylates, Tin(IV) Iodide, and Tetrabutylammonium Iodide Controlled by Either a Steric Effect or Coordination Effect

Abstract

A combination of tin(IV) iodide and tetrabutylammonium iodide can be used for propargylation or allenylation of aldehydes with 2-propynyl mesylates in dichloromethane. 1-Methyl-2-propynyl mesylate or 2-butynyl mesylate results in propargylation or allenylation controlled by the steric effect of the 1- or 3-methyl group, and 3-trimethylsilyl-2-propynyl mesylate results in propargylation controlled by the coordination of triiodostannate to silane.

Key words

nucleophilic addition - propargylation - allenylation - tin(IV) iodide - tetrabutylammonium iodide

References and Notes

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9

It was confirmed by ¹H NMR analysis (JEOL Λ-500) that the reaction of 4 (0.03 mmol) with SnI₂ (0.04 mmol) and NaI (0.04 mmol) in DMF-d ₇ (0.5 mL) at 25 °C first produced propargyltin A, δ = 4.06 ppm (CH₂, s), and then produced a small yield of allenyltin C, δ = 4.90 ppm (C = CH₂, s).