101161-98-2Relevant articles and documents
Aromatic Benzhydrylation: Part IV - Syntheses of Triarylmethane Group of Chalcones, Flavanones, Flavones, Chromones and 2-Methylchromones using Benzhydrylation of Phloroacetophenone, Gallacetophenone and 5,7-Dihydroxyflavanones
Jain, A. C.,Nayyar, Naresh K.,Shrivastava, Rene
, p. 1023 - 1031 (2007/10/02)
Phloroacetophenone reacts with diphenylcarbinol in the presence of BF3-C2H5OC2H5 to give its 3-diphenylmethyl (2d, 25percent yield) and 3,5-bisdiphenylmethyl derivatives (2e, 17.4percent yield) along with a small amount of dibenzhydryl ether (1). 2d on either heating with Ac2O-NaOAc at 180 deg C or treating with CH3SO2Cl, DMF and BF3-C2H5OC2H5 affords only the corresponding 6-diphenylmethylchromone (3b or 5f) as established by PMR data and direct comparison with an authentic sample.A similar reaction of 2a yields 3a and 5a.Alkaline hydrolysis of 3a and 3b gives the corresponding benzhydrylated 2-methylchromones (4a and 4f).Compounds 2b and 2e have been converted into benzhydrylated chalcones (6a and 6b respectively) and flavones (8a and 8f respectively) by standard methods without any difficulty.However, isomerisation of 6a gives the flavanone 7c in a poor yield.A better method of preparing benzhydrylated flavanones involves direct benzhydrylation of hydroxyflavanones.Thus, 5,7-dihydroxyflavanone (7l) gives a separable mixture of 7a, 7f and 7j.Gallacetophenone on benzhydrylation gives mainly its 5-diphenylmethylderivative (9a) which can be converted into the corresponding chromones (11a and 11c) and chalcone (10).Structures of all the products have been established by elemental analysis and PMR data.
Aromatic Benzhydrylation: Part III - Synthesis of Chromones of Triphenylmethane Type
Jain, A. C.,Gupta, S. M.,Bambah, Pawan
, p. 393 - 397 (2007/10/02)
2-O-Methylphloroacetophenone (1) when treated with diphenylcarbinol in the presence of boron trifluoride etherate and dioxan gives a mixture of 3-C-benzhydryl-(4a), 5-C-benzhydryl-(3a) and 3,5-di-C-benzhydryl-(2a) derivatives in 19.7, 14.8 and 6.7percent yields respectively.Location of benzhydryl unit in 3a and 4a has been made (i) by NOE studies and (ii) by converting them into 7d and 8d respectively via 3b and 4b and comparing them with authentic 7d and 8d prepared by benzhydrylation of 5,7-dihydroxychromone (5) followed by methylation of the products (7a and 8a).Locationof benzhydryl unit in 7a and 8a can be made by comparing the PMR spectra of their methyl ethers and acetates
