ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Preparation of α -methyl- γ -butyrolactone: Mechanism of its formation and utilization in 2-methyl-1-tetralone synthesis

Vladislav Semak, Andrej Boháč, Marta Sališová, Gabriela Addová, and Peter Danko

Department of Organic Chemistry, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovakia

E-mail: bohac@fns.uniba.sk

Received: 21 July 2007  Revised: 15 October 2007  Accepted: 16 October 2007

Abstract: α-Methyl-γ-butyrolactone (III) has been prepared directly from γ-butyrolactone (I) in 89 % yield by selective monomethylation conditions: K₂CO₃/DMC/210°C/7 h. The reaction mechanism was elucidated and described. An intermediate and two byproducts: methyl tetrahydro-3-methyl-2-oxofuran-3-carboxylate (II), 3-(methoxycarbonyl)propyl methyl carbonate (IV) and 3-(methoxycarbonyl)butyl methyl carbonate (V) were identified. The high temperature disproportionation of K₂CO₃ in the presence of dimethyl carbonate to MeOK was observed. The new selective synthesis of 2-methyl-1-tetralone (VI) from α-methyl-γ-butyrolactone (III) by Friedel-Crafts conditions was performed in 79 % yield.

Keywords: dihydro-3-methylfuran-2(3H)-one -  α-methyl-γ-butyrolactone - dimethyl carbonate - reaction mechanism - selective monomethylation - 2-methyl-1-tetralone - 

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-008-0023-1

Chemical Papers 62 (3) 275–280 (2008)