PREPARATION OF CYCLOMANGANATED CHALCONES AND THEIR REACTIONS WITH METHYL ACRYLATE AND OTHER ALPHA,BETA-UNSATURATED CARBONYL-COMPOUNDS

Chalcones [(E)-1,3-diarylprop-2-en-1-ones] react with benzyltetracarbo nylmanganese under reflux in petroleum spirit to give two types of cyc lomanganation products. The first, involving metallation at the alkeny l beta-carbon of the enone, are derivatives of [[1-phenyl-2-phenylcarb onyl-kappa O]ethenyl-kappa C-1]tetracarbonylmanganese, while the secon d type, manganated at the aryl ring ortho-carbon, are derivatives of [ 2-[3-phenylprop-2-en-1-onyl-kappa O]phenyl-kappa C-1]tetracarbonylmang ane In general, more ''alkene-manganated'' than ''ring-manganated'' pr oduct is formed, with the ratio influenced significantly by certain su bstituents, e.g. a 4-CF3 substituent on the phenyl ring at C3 of the e none strongly promotes ''alkene-manganation''. in some cases there are minor by-products derived from coupling of two chalcone molecules aft er initial cyclomanganation. The crystal structures are reported for t wo such products, rifluoromethylphenyl)-6-methoxy-2-indanylcarbonyl- k appa O)-6-methoxyphenyl-kappa C-1]tetracarbonylmanganese and 4-di-(4-t rifluoromethylphenyl)cyclopent-2-en-1-ol. In acetonitrile under reflux , alkene-manganated chalcones react with methyl acrylate (methyl prope noate) to form derivatives of methyl (E)-4,6-diphenyl-6-oxohex-2-enoat e and of ethoxycarbonylethyl)-3,5-diphenylfuran-2-(5H)-one. The latter butenolides are not formed when the reactions are carried out in carb on tetrachloride, only the former alpha,beta-unsaturated esters. By co ntrast, in a few reactions studied, acrolein (propenal) and methyl vin yl ketone (but-3-en-2-one) give only the butenolide products when trea ted with alkene-manganated chalcones in refluxing acetonitrile. An exc eption is the reaction of methyl vinyl ketone with [[1 -trimethoxyphen yl)-2-(4-chlorophenylcarbonyl-kappa O)]ethenyl-kappa C-1]tetracarbonyl manganese to form the cyclized product nyl)3-(3,4,5-trimethoxyphenyl)c yclopent-2-en-1-ol.