Process for preparing 2-acyl-5-substituted thiatetrahydrofuran-4-ones

A process for preparing at least one member of the genus of 2-acyl-5-substituted thiatetrahydrofuran-4-one compounds defined by the structure:

• comprising the steps of (i) dimerizing in the presence of a basic material one or more C.sub.4 -C.sub.6 alpha, beta diketones having the structure:
• ##STR29## to form one or more alpha, beta diketone dimers defined by the structure:
• ##STR30## and then, (ii) reacting a mercaptan having the formula R.sub.3 SH with said alpha, beta diketone dimer or said alpha, beta diketone dimers in the presence of an acid catalyst thereby producing one or more compounds defined by the structure:
• ##STR31## wherein R.sub.1, R.sub.2, R.sub.1 ' and R.sub.2 ' are the same or different and each represents hydrogen or methyl and wherein R.sub.3 represents one of C.sub.1 -C.sub.9 alkyl, benzyl, phenyl, substituted or unsubstituted allyl having the structure:
• ##STR32## 3-furyl substituted or unsubstituted having the structure:
• ##STR33## oxy or hydroxy alkyl having the structure:
• ##STR34## wherein Q is:
• ##STR35## and R.sub.5 and R.sub.6 are the same or different lower alkyl taken separately or, taken together, R.sub.5 and R.sub.6 complete a cyclialkyl ring;
• and wherein each of R.sub.4, R.sub.7 and R.sub.8 are the same or different and are hydrogen or methyl, and wherein R.sub.11 and R.sub.12 are the same or different and each both represent hydrogen or each both represent methyl or one of R.sub.11 or R.sub.12 is hydrogen and the other of R.sub.11 or R.sub.12 is methyl;
• the total number of moles of methyl groups and hydrogen groups constituting R.sub.11 and R.sub.12 being equivalent to the total number of moles of methyl groups and hydrogen groups constituting R.sub.1, R.sub.2, R.sub.1 ' and R.sub.2 '.