Organocatalyzed Visible Light-Mediated gem-Borosilylcyclopropanation.

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.

Synthesis of 2-substituted bicyclo[1.1.0]butanes via zincocyclopropanation using bromoform as the carbenoid precursor.

Through a revisited Simmons-Smith type zincocyclopropanation using bromoform as the carbenoid source, the synthesis of 2-, 2,2- and 2,4-substituted bicyclo[1.1.0]butanes is reported. Few antecedents of the derivatives have yet been described. Ultimately, the underexplored scaffolds exhibited a complete discrepency of reactivity.