Alkyloximes and Imines via Silyl Carbamates

Abstract

The reactions between different N,O-bis-trimethylsilyl-carbamates and oxo compounds were studied. The N,O-bis-trimethylsilyl-N-methoxy-carbamate converts ketones to the corresponding O-methyl oximes. The product is usually a mixture of syn and anti isomers. If the carbonyl compound bears a hydroxyl group, the oxime formation and the O-silylation take place simultaneously. In the case of α-haloketones, the undesired substitution of halogen was not observed. The reactions between N,O-bis-trimethylsilyl-N-methyl-carbamate and oxo compounds resulted in the corresponding imines, although the yield are moderate in some cases. Analoguos reaction of ferrocenylated oxo derivatives gave similar results.

Keywords:

• Carbamates
• ferrocene derivatives
• O-methyl oxime
• imines
• silicon and carbonyl compounds

ACKNOWLEDGMENT

This work was supported by the Hungarian National Science Foundation (OTKA) Grant Nos. F030821 and T025830.

Notes

^a Molar ratio of oxo compound and N,O-bis-trimethylsilyl-N-methyl-carbamate.

^b Molar ratio of trifluoroacetic acid catalyst and oxo compound.

^c With N,O-bis-trimethylsilyl-N-trimethylsiloxy-carbamate.

^a Molar ratio of oxo compound and N,O-bis-trimethylsilyl-N-methyl-carbamate.

^b Molar ratio of trifluoroacetic acid catalyst and oxo compound.

^c Not isolated; even repeated distillation resulted in a mixture of the product and the starting ketone.