258831-59-3Relevant articles and documents
A facile and convenient synthesis of new substituted heteroarylchalcones and flavones by microwave irradiated suzuki-miyaura cross coupling reaction in aqueous medium
Joshi, Vidya,Hatim, Jaywant Govind
, p. 281 - 288 (2013/09/24)
Chalcones 6a-g and corresponding flavones 7a-g having various heteroaryl substituents have been synthesized. The starting compound 5-formyl-2- methoxyboronic acid 3 was prepared by a series of reactions; Bromination of 4-methoxybenzaldehyde (4-CH3O-C8H4-CHO) with catalyst, anhyd AICI3 in DCE (1,2-dichloroethane) gave 3-bromo-4-methoxybenzaldehyde 1. The aldehydic group from 3-bromo-4- methoxybenzaldehyde 1 was protected by acetalization with 1,3-propane-diol and ethyl orthoformate with phase transfer catalyst tetrabutylammonium tribromide (TBATB) producing the corresponding 2-(3-bromo-4-methoxyphenyl)-1,3-dioxan 2 which on treatment with trimethyl borate [(MeO)3B] in presence of n-butyllithium at 70° gave 5-formyl-2-methoxyboronic acid 3. Suzuki-Miyaura coupling of 3 with different heteroaryl bromides 4a-g in presence of [(C 6H5)3P]4Pd (0) catalyst, aq.Na 2CO3 (2N) as base and aq DMF (N,N-dimethylformamide) as solvent and micro-wave irradiation for 1 to 2.5 min. in a Panasonic microwave set at 1000 Watts and 80% microwave power, yielded 3-heteroaryl-4- methoxybenzaldehydes 5a-g. Claisen-Schmidt condensation of 5a-g with 2-hydroxyacetophenone in presence of ethanolic KOH produced 3-heteroaryl- 2′-hydroxy-4-methoxychalcones 6a-g. On cyclizing with a mixture of l 2 and DMSO, chalcones 6a-g gave 3'-heteroaryl-4′- methoxyflavones 7a-g.
