Reaction of N-substituted 2-oxochromen-3-carboxamides with bromoderivatives of zinc enolates prepared from alkyl 2,2-dialkyl-4,4-dibromo-3-oxoalkanoates and zinc
作者:V. V. Shchepin、P. S. Silaichev、N. Yu. Russkikh、M. I. Vakhrin、M. I. Kodess
DOI:10.1134/s1070428006080094
日期:2006.8
Zinc enolates obtained from ethyl 2,2-dialkyl-4,4-dibromo-3-oxobutanoates and zinc react with N-substituted 2-oxochromen-3-carboxamides forming ethyl 3-1a-(R(3)-carbamoyl)-2-oxo-1a,7b-dihydrocyclopropa[c]chromen-1-yl}-2,2-dialkyl-3-oxopropanoate isomer with a Z-position of methine hydrogens. Zinc enolates prepared from alkyl 2,2-dialkyl-4,4-dibromo-3-oxopentanoates and -hexanoates and zinc react with N-substituted 2-oxochromen-3-carboxamides to give rise to esters of 3-1-alkyl-1a-(R(3)-carbamoyl)-2-oxo-1a,7b-dihydrocyclopropa[c]chromen-1-yl}-2,2-dialkyl-3-oxopropanoic acid as isomers with the E-position of the methine proton and the alkyl substituent. The reaction carried out in the presence of small quantities of THF and HMPA leads to the formation of 9c-alkyl-2-R(3)-9b,9c-dihydro-5-oxa-2-azacyclopenta[2,3]-cyclopropa[1,2-a]naphthalene-1,3,4-triones. Zinc enolates from alkyl 2,2-dialkyl-4,4-dibromo-3-oxopentanoates and -hexanoates and zinc with the secondary amides of 2-oxochromen-3-carboxylic acid form alkyl 3-2-oxo-1a-(piperidinocarbonyl)- and 3-6-R(1)-1a-(morpholinocarbonyl)-2-oxo-1a,7b-dihydrocyclopropa[c]chromen-1-yl)-2,2-R(2),R(2)-3-oxopropanoates as single geometrical isomers.