Synthesis and spectroscopic studies of isosteviol-calix[4]arene and -calix[6]arene conjugates

Korochkina, M. G.; Fontanella, Marco Maria; Casnati, Alessandro; Arduini, Arturo; Sansone, Francesco; Ungaro, Rocco; Latypov, Shamil K.; Катаев, В. Е.; Al’fonsov, V. A.

doi:10.1016/j.tet.2005.03.127

Cited by 28 publications

(18 citation statements)

References 29 publications

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“…The observed chemical shifts and spin-spin coupling constants in the 1 H NMR spectrum of the reaction mixture are consistent with those reported for 13α,16α,17-trihydroxy-ent-kaur-19-oic acid (VIII) which was synthesized by enzymatic hydrolysis of suavioside isolated from sweet leaves of Rubus Suavissimus [8]. The 1 H NMR spectrum also contained a doublet of doublets at δ 2.68 ppm, which is typical of the 15α-H proton in ent-beyerane skeleton [9], singlets at δ 0.81 and 1.26 ppm due to C 20 H 3 and C 18 H 3 groups in entbeyerane [9], and doublets at δ 3.51 and 3.64 ppm, which belong to methylene protons of hydroxymethyl group. These data indicated that the second reaction product is 17-hydroxy-ent-16-oxobeyeran-l9-oic acid (IV), i.e., diterpenoid having ent-beyerane (isosteviol) structure.…”

supporting

confidence: 82%

Wagner-Meerwein rearrangement of steviol 16α,17- and 15α,16-epoxides

et al. 2010

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16α,17-and 15α,16-Epoxy derivatives of diterpenoid steviol having ent-kaurane structure were found for the first time to undergo Wagner-Meerwein rearrangement in alkaline medium or by the action of boron trifluoride-diethyl ether complex to give products with ent-beyerane structure. The geometric parameters of steviol 16α,17-and 15α,16-epoxides were determined by X-ray analysis.In the recent years, studies on biotransformations of diterpenoid steviol (I, 13-hydroxy-ent-kaur-16-en-19-oic acid) having ent-kaurane structure and its epoxy derivative II have been reported [1][2][3][4]. Epoxide hydrolases isolated from various microorganisms are universal biocatalysts for asymmetric hydrolysis of epoxides [4], and alcohols thus formed exhibit diverse biological activity, in particular hormone [3] and antihyperglycemic [2]. As concerns chemical modification of steviol epoxides II and V, their hydrolysis in the presence of mineral [5] and Lewis acids [6] and reduction with lithium tetrahydridoaluminate [6] were reported (Schemes 1, 2). In most cases, these reactions are accompanied by the Wagner-Meerwein rearrangement with formation of products having ent-beyerane (isosteviol) skeleton, i.e., compounds IV (Scheme 1) [5,6], VI, and VII [6] (Scheme 2). In the present article we describe opening of the oxirane rings in steviol 16α,17-and 15α,16-epoxides II and V by the action of Lewis acid (boron trifluoride-diethyl ether complex BF 3 · Et 2 O).Epoxide II was synthesized by oxidation of steviol (I) with m-chloroperoxybenzoic acid by analogy to the procedure reported in [7]. Compound II was assigned

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confidence: 82%

Wagner-Meerwein rearrangement of steviol 16α,17- and 15α,16-epoxides

et al. 2010

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“…Thus the yields of macrocycles 15 and 16 were very similar at the acid chloride -pyridine ratio both 1:70 and 1:900. The 1 H NMR spectra of compounds 14-16 showed just a one set of signals characteristic for isosteviol 1 and its derivatives, [11][12][13]20,21,25,29] namely three singlets corresponding to С 18 Н 3 ,…”

Section: Resultsmentioning

confidence: 99%

Macrocyclic Derivatives of Diterpenoid Isosteviol with Hydrazide and Hydrazone Moieties

Garifullin¹,

Andreeva²,

Strobykina³

et al. 2013

MHC

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“…In addition, we analyzed relevant literature data. 12, 13 The signal at δ 2.18 in the spectrum of isosteviol (1) (12) and H e (3). In our case, the downfield shift of this signal is even larger when moving from isosteviol (1) to acid chloride 2.…”

Section: Resultsmentioning

confidence: 99%