The [4+2] cycloaddition between 2,4-diphenylpyrimidine ortho-quinodimethane and dimethyl acetylenedicarboxylate leads to 2,4-diphenylquinazoline-6,7-dicarboxylate (6). 2,4-Diphenylfuro[3,4-g]quinazoline-6,8-dione (7) is also obtained by basic hydrolysis of compound 6, followed by the closure of the resulting diacid in acetic anhydride.
Substituted 6,7-Dihydro-5H-benzocyclohepta[1,2-d]pyrimidines. -The synthesis of 2,4-bis(dialkylamino) derivatives (III) of benzocycloheptapyrimidines is smoothly achieved on two facile pathways. The first involves the thermally induced cyclization of the vinyl triflate derivative of benzosuberone (I) with cyanamides (II). Attempted direct cyclization of benzosuberone with cyanamides in the presence of triflic anhydride unexpectedly affords triazines as cyclotrimerization products of cyanamides. The second synthetic access to title compounds (III) is based on the substitution of methylsulfonyl groups in compound (V) with amines. -(HERRERA, A.; MARTINEZ-ALVAREZ*, R.; CHIOUA, R.; BENABDELOUAHAB, F.; CHIOUA, M.; Tetrahedron 60 (2004) 25, 5475-5479; Dep. Quim. Org., Fac. Cienc. Quim., Univ. Complutense, E-28040 Madrid, Spain; Eng.) -Mischke 40-159
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