Allahdad, Ahmad; Knight, David W. published the artcile< An investigation of the Wittig reaction between a series of monosubstituted phthalic anhydrides and ethoxycarbonylmethylidenetriphenylphosphorane>, Safety of 4-Bromoisobenzofuran-1,3-dione, the main research area is Wittig phthalic anhydride ethoxycarbonylmethylidenetriphenylphosphorane regiochem; ylidenephthalide; phthalide ylidene.
The reaction was examined of EtO2CCH:PPh3 (I) with II (Z = Z1 = O, R = x-OMe, x-NMe2, x-Me, x-CO2Me, x-NO2, x-Cl, x-Br; x = 3,4) in refluxing dry CHCl3 for 18 h. The structures of the products II (Z ≠ Z1 = O, CHCO2Et, R as before) were determined by chem. and spectral methods. The regioselectivity of the reaction is governed by substituent electronic effects which render one of the anhydride CO groups more susceptible to nucleophilic attack. Generally, (E)-ylidenephthalides were formed predominantly. II (Z = Z1 = O, R = 3-Me) with I gave a 73:23:4 mixture of (E)-II (Z = CHCO2Et, Z1 = O, R = 3-Me) [(E)-III], (Z)-III, and (Z)-II (Z = O, Z1 = CHCO2Et, R = 3-Me); II (Z = Z1 = O, R = 3-Cl) gave a 43:52:5 mixture of (E)-II (Z = CHCO2Et, Z1 = O, R = 3-Cl) [(E)-IV], (Z)-IV, and (Z)-II (Z = O, Z1 = CHCO2Et, R = 3-Cl), resp.
Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999) published new progress about Regiochemistry. 82-73-5 belongs to class bromides-buliding-blocks, and the molecular formula is C8H3BrO3, Safety of 4-Bromoisobenzofuran-1,3-dione.
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary