Organocatalyzed Visible Light-Mediated <i>gem</i>-Borosilylcyclopropanation
Léa Thai‐Savard, Morgane Sayes, Josiane Perreault-Dufour, Gang Hong, Lucille A. Wells, Marisa C. Kozlowski, André B. Charette
Abstract
The borosilylcyclopropanation of styrene derivatives using a (diiodo(trimethylsilyl)methyl)boronic ester carbene precursor is reported herein. The key reagent was synthesized in a 4-step sequence using inexpensive and commercially available starting materials. This method enabled the preparation of novel 1,1,2-tri- and 1,1,2,2-tetrasubstituted borosilylcyclopropanes up to excellent yields and diastereoselectivity. The reaction is organocatalyzed by eosin Y in the presence of visible light. A mechanism consistent with the experimental observations was postulated based on density functional theory calculations. The versatility of these entities was highlighted through post-functionalization reactions.