Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content.
20.2.12.1.1.2.1 Variation 1: Use of Magnesium Methyl Carbonate

DOI: 10.1055/sos-SD-020-00556

Beignet, J.Science of Synthesis, (200720571.

Magnesium methyl carbonate (6) is a useful agent for carboxylation of ketones, and has been employed in the preparation of β-oxo acids (Scheme 3).[‌1‌,‌2‌,‌22‌] This method was originally applied to the synthesis of 3-oxoalkanoic acids monosubstituted at the 2-position.[‌22‌] This process appears to be highly regioselective when using methyl ketones 5 and produces the β-oxo acids 8.[‌1‌,‌2‌] The driving force of this reaction probably originates from the formation of the chelate 7, and would explain the failure of the carboxylation of ketones possessing only one α-hydrogen.[‌23‌] The regioselectivity of this method is also explained by this chelate. Carboxylation is reversible at high temperature and the product might reflect the relative stability of two possible isomeric magnesium chelates.[‌23‌] Practically, this method is high yielding but requires the use of a large excess of magnesium methyl carbonate in dimethylformamide at high temperature.

Meeeee 8 Meeeeeeeeeeee ee Meeeee Meeeeee eeee Meeeeeeee Meeeee Meeeeeeee[‌8‌,‌8‌,‌88‌]

Meeeeee Meeeeeeee

8-Meeeeeeeeee Meeee 8; Meeeeee Meeeeeeee:[‌8‌,‌88‌]

M eeee ee eee eeeeee eeeeee 8 eee eeeeeeeee eeeeee eeeeeeeee (8; 888 eeeee) eee eeeeee ee 888888°M ee MMM eee 888e. Mee eeeeeee eee eeeeee eee eeeeee eeee eee eee eeeeee MMe eeee eeeeeeee. Mee eeeeeee eee eeeeeeeee eeee Me8M eee eee eeeeeee eeeee eee eeeeeeeee eeee 8% MeMMM8 eeee. Meee eeeeeee eeeee eee eeee eeeeeeeee ee 8°M eee eeeeeeeee eeee Me8M. Mee eeeeeee eeeeeeee eeee eeeee eee eeeeeeeeeeee ee eeeeee eee β-eee eeee.

References


Cookie-Einstellungen