PROCESS FOR THE PREPARATION OF 7-SUBSTITUTED 3-ALKYL-3H-ISOBENZOFURAN-1-ONE DERIVATIVES

摘要

Process for the preparation of compounds of formula (I) wherein R is halogen, R1O1R1S(O)n or (R1)2NC(X)O; R1 is C1-C8alkly, aryl-C1-C8alkyl, C1-C8haloalkyl or aryl; n is 0, 1, 2 or 3; X is O or S; and R2 is hydrogen, C1-C4alkyl or C1-C4haloalkyl, in which process, in a solvent, (1) an aniline derivative of formula (IV) wherein R is as defined above, and R3 is C1-C5alkyl or C1-C5haloalkyl, is diazotised in the presence of a mineral acid to form the corresponding diazonium salt of formula (II) wherein R and R3 are as defined above, A is an anion, and m is 1 or 2, (2) the resulting diazonium salt of formula (II) is carbonylated in the presence of a catalyst, CO and optionally a buffer, to form a benzoic acid derivative of formula (III) wherein R and R3 are as defined above, and (3) the benzoic acid derivative of formula (III) is then subjected to benzylic lactonisation in the ortho-position alkyl chain R3 in the presence of a free-radical initiator and a halogenating agent.