Crystal Structure of 3,4-Dihydro-2-methoxy-2-methyl-4-phenyl-2H,5H-pyrano[3,2-c]chromen-2-one
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CTURE OF ORGANIC COMPOUNDS
Crystal Structure of 3,4-Dihydro-2-methoxy-2-methyl-4-phenyl2H,5H-pyrano[3,2-c]chromen-2-one A. N. Kochetova,*, L. A. Nosikovaa, and L. G. Kuz’minab aMIREA—Russian
Technological University (Lomonosov Institute of Fine Chemical Technologies), Moscow, 119571 Russia b Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia *e-mail: [email protected] Received March 11, 2020; revised March 11, 2020; accepted April 3, 2020
Abstract—A new polymorph of 3,4-dihydro-2-methoxy-2-methyl-4-phenyl-2H,5H-pyrano[3,2c]chromen-2-one (pyranocoumarin) was studied by X-ray diffraction. The crystallographic parameters of the structure of C20H18O4 are M = 322.34, sp. gr. C2/c, a = 23.542(1) Å, b = 8.4938(3) Å, c = 19.7804(8) Å, β = 125.977(3)°, Z = 8. DOI: 10.1134/S1063774520050119
INTRODUCTION The structure of the molecular complex of the anticoagulant agent 3-[1-(4-nitrophenyl)-3-oxobutyl]-4hydroxychromen-2-one (the brand name Syncumar) with ethanol was determined in [1]. Solvated forms of some 4-hydroxycoumarin derivatives exhibit higher pharmaceutical activity [2] and are of interest as new drug candidates and rodenticides. Previously, some derivatives of this drug group were found to be highly toxic. For example, methyl ether of the pharmacopoeial drug Warfarin is more toxic against M. Musculus L. than Warfarin [3, 4]. A large number of polymorphs of derivatives of this drug group were described in the literature [5–7]. In particular, this accounts for a wide range of spectral characteristics and melting points of the derivatives synthesized by different methods [8–11]. Some medicinal substances are known to exist in more than five polymorphs [7, 12]. The preparation of a polymorphic form may be associated with the formation of different solvates, self-condensation products, or interactions with the solvent. Meanwhile, taking into account the differences in pharmacological characteristics of polymorphs of the same drug, the preparation and purification of drug formulations should be performed under strict regulatory guidelines [13]. The above factors promote great interest in research on the structure of Warfarin [9, 14] and its methyl ether [10] as the most widely available drug of this group. In the crystalline state, Warfarin exists solely as a cyclic hemiacetal [9, 10, 14–16]. However, open-chain forms of this compound are observed in solution due to the opening of the hemiacetal moiety [16–19].
Both cyclic and alicyclic forms of methyl derivatives of Warfarin were isolated depending on the method for their preparation [10]. The methylation of Warfarin with diazomethane [20] and iodomethane affords the same methyl ether of the open-chain form [10]. The crystallization of Warfarin from methanol did not result in the formation of derivatives; however, a solvated form containing MeOH in a ratio of 1 : 1 was obtained in [14]. The reaction of Warfarin with appropriate alcohol in the presence of hydrochloric acid or Dowex 50 resin can be used to prepare eth
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