The First Allylation of Imines with Allyltrichlorosilanes Using Neutral Coordinate-Organocatalysts

Abstract

Imines derived from aldehydes and 2-aminophenols reacted with allyltrichlorosilanes in the presence of DMF, HMPA, or pyridine N-oxide as a neutral coordinate-organocatalyst to afford the corresponding homoallylic amines in high yields with high stereoselectivity; this is the first example of allylation of imines with allyltrichlorosilanes.

Key words

allylations - imines - catalysis - neighboring-group effects - stereoselective

References

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5

General procedure for allylation: To a solution of imine 3 (0.3 mmol) and 2-methyl-2-butene (0.3 mmol) in DMF (0.3 mL) was added dropwise allylic trichlorosilane 4 or 6 (1.5 equiv) at 0 °C. After stirring vigorously for 5 h at the same temperature, triethylamine (0.2 mL) in methanol (1.0 mL) was added to quench the resulting viscous solution. The mixture was diluted with diethyl ether (40 mL) and water (20 mL). The organic layer was separated, washed twice with water (20 mL), dried over anhydrous Na₂SO₄, filtered, and purified by preparative TLC (hexane/ethyl acetate, 6:1) to give adduct 5 or 7.

8

Products 8 were prepared from crotylation of 2-amino-p-cresol/benzaldehyde-imine under the conditions similar to crotylation of 3a (Scheme [1] ). The reactions with (E)- and (Z)-6 at r.t. for 5 h provided syn-8 (74% yield, 86% syn) and anti-8 (76% yield, >99% anti), respectively.