- Structural requirements for the antifungal activities of natural drimane sesquiterpenes and analogues, supported by conformational and electronic studies
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Seventeen drimanes including polygodial (1), isopolygodial (2), drimenol (3) and confertifolin (4) obtained from natural sources and the semi-synthetic derivatives 5-17 obtained from 1-3, were evaluated in vitro for antifungal properties against a unique panel of fungi with standardized procedures by using two end-points, MIC100 and MIC50. A SAR analysis of the whole series, supported by conformational and electronic studies, allowed us to show that the Δ7,8 -double bond would be one of the key structural features related to the antifungal activity. The MEPs obtained for active compounds exhibit a clear negative minimum value (deep red zone) in the vicinity of the Δ7,8 -double bond, which is not present in the inactive ones. Apart of this negative zone, a positive region (deep blue) appears in 1, which is not observed either in its epimer 2 nor in the rest of the active compounds. The LogP of active compounds varies between 2.33 and 3.84, but differences in MICs are not correlated with concomitant variations in LogP values.
- Derita, Marcos,Montenegro, Ivan,Garibotto, Francisco,Enriz, Ricardo D.,Fritis, Mauricio Cuellar,Zacchino, Susana A.
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p. 2029 - 2051
(2013/04/10)
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- An efficient total synthesis of isodrimeninol from zamoranic acid
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An efficient total synthesis of isodrimeninol (1) has been achieved from zamoranic acid (3) employing a regioselective Lewis acid mediated elimination-isomerisation as the key step. Following oxidative cleavage of the resulting conjugated diene to the methyl ketone, standard manipulations allowed the synthesis of allylic alcohols 10 which, after a highly diastereoselective epoxidation and subsequent lactonisation, allowed the synthesis of the natural product in 11 steps and 56% overall yield.
- Marcos, Isidro S.,Moro, Rosalina F.,Carballares, Santiago M.,Urones, Julio G.
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p. 541 - 543
(2007/10/03)
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- Oxo Complexes of Ruthenium(VI) and (VII) as Organic Oxidants
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Oxidation of a variety of saturated and unsaturated primary and secondary alcohols by tetraoxoruthenate(VI), 2-, tetraoxoruthenate(VII), -, barium trans-trioxodihydroxoruthenium(VI), trans-Ba, dioxotrichlororuthenate(VI), -, and dioxodichlorobipyridylruthenate(VI),, has been studied; 2- may be used catalytically in conjunction with 2- under basic aqueous conditions.For some of these systems, the oxidation of several aldehydes and amines were also examined.Both 2- and - oxidise primary alcohols to carboxylic acids and secondary alcohols to ketones; the reactivity of these reagents towards unsaturated alcohols was studied in particular.The new species and also cleanly oxidise a wide range of alcohols to aldehydes and ketones without attack of double bonds.Ba functions as a heterogeneous oxidant in dichloromethane, oxidising only the most reactive alcohols to aldehydes.
- Green, Graham,Griffith, William P.,Hollinshead, David M.,Ley, Steven V.,Schroeder, Martin
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p. 681 - 686
(2007/10/02)
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- The Diels-Alder Route to Drimane related Sesquiterpenes; Synthesis of Cinnamolide, Polygodial, Isodrimeninol, Drimenin and Warburganal
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The stereospecific preparation of various 1-vinyl-2,6,6-trimethylcyclohex-1-enes (6) as potential diene precursors in the Diels-Alder reaction with dimethyl acetylenedicarboxylate have been investigated.The reaction of the parent diene (6a) with dimethyl acetylenedicarboxylate affords an adduct (18) in 94percent yield.This species was reductively isomerised using 10percent Pd/C/H2 and a mineral acid to give a trans-fused decalin diester (19).Reduction of (19) with lithium aluminium hydride afforded 1,4,4a,5,6,8,8a-octahydro-5,8,8a-trimethyl-1β,4aα,8aβ-naphthalene-1,2-dimethanol (24) a key starting material for the highly efficient syntheses of five drimane sesquiterpene natural products, cinnamolide (1), polygodial (2), isodrimeninol (3), drimenin (4), and warbuganal (5).Microbial oxidation reactions using C. elegans or A. niger of (2), (24), and (1) gave good yields of the corresponding 3β-hydroxy derivatives, (30), (31), and (32).Several other unusually substituted drimane derivatives are reported.
- Hollinshead, David M.,Howell, S. Christopher,Ley, Steven V.,Mahon, Michael,Ratcliffe, Norman M.,Worthington, Paul A.
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p. 1579 - 1589
(2007/10/02)
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