Abstract: The present invention relates to the derivatives of the formula ##STR1## in which: A is an aromatic ring or a nitrogen heterocycle;X.sub.1, X.sub.2, X.sub.3 and X.sub.4 are independently a hydrogen atom, a halogen atom, a lower alkyl radical, a C.sub.3 -C.sub.7 cycloalkyl radical, an alkoxy radical, an alkylthio radical, a sulfone group, SO.sub.2 -lower alkyl, a sulfoxide group, SO-lower alkyl, a trifluoromethyl group, a nitro group, a hydroxyl group, a methylene alcohol radical or a group COOR', in which R' is a hydrogen or a lower alkyl; X.sub.3 and X.sub.4 can also form a naphthalene with the phenyl;B is CR.sub.5 R.sub.6, R.sub.5 and R.sub.6 being a hydrogen atom, a lower alkyl or a C.sub.3 -C.sub.7 cycloalkyl radical, or the sulfur atom;R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently a hydrogen atom, a lower alkyl radical or a C.sub.3 -C.sub.7 cycloalkyl radical; CR.sub.1 R.sub.2 or CR.sub.3 R.sub.4 can form with B, when the latter is CR.sub.5 R.sub.

Abstract: The present invention relates to the derivatives of the formula ##STR1## in which: A is an aromatic ring or a nitrogen heterocycle;X.sub.1, X.sub.2, X.sub.3 and X.sub.4 are independently a hydrogen atom, a halogen atom, a lower alkyl radical, an alkoxy radical, an alkylthio radical, a sulfone group, a sulfoxide group, a trifluoromethyl group, a nitro group, a hydroxyl group, a methylene alcohol radical or a group COOR', in which R' is a hydrogen or a lower alkyl; X.sub.3 and X.sub.4 can also form a naphthalene with the phenyl;B is CR.sub.5 R.sub.6, R.sub.5 and R.sub.6 being a hydrogen atom or a lower alkyl, or the sulfur atom;R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently a hydrogen atom or a lower alkyl radical; CR.sub.1 R.sub.2 or CR.sub.3 R.sub.4 can form with B, when the latter is CR.sub.5 R.sub.6, a cycloalkyl or a cycloalkene having 3 to 7 carbon atoms; R.sub.1 R.sub.2 and R.sub.3 R.sub.4 can also form a ring having 3 to 6 carbon atoms;n is an integer from 1 to 4 and can be 0 if R.sub.1 and R.

Abstract: The invention relates to novel monoesters and diesters of 9,10-endoethano-9,10-dihydroanthracene-11,11-dicarboxylic acid.These novel monoesters and diesters correspond to the following structural chemical formula (II): ##STR1## in which R.sup.1 and R.sup.2 are identical or different and can represent H, an alkali metal or alkaline earth metal atom, a linear or branched alkyl group having from 1 to 6 carbon atoms, an alicyclic group having from 3 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, defined in their cis or trans variety, or an alkynyl group having from 2 to 6 carbon atoms, the said groups optionally being substituted by one or more functional groups such as ether, epoxide, halogeno, cyano, ester, aldehyde, ketone, aryl etc., where R.sup.1 and R.sup.2 cannot be H or ethyl simultaneously. These addition products constitute valuable intermediates for the preparation of methylidenemalonates in high yields and with a high purity.