ABSTRACT
The reaction of geraniol with different lithium carbenoids generated from n-BuLi and the corresponding dihaloalkane has been evaluated. The reaction occurs in a chemo and stereoselective manner, which is consistent with a directing effect from the oxygen of the allylic moiety. Furthermore, a set of polyenes containing allylic hydroxyl or ether groups were chemoselectively and stereoselectively converted into the corresponding gem-dimethylcyclopropanes in one single step in moderate to good yields mediated by a lithium carbenoid generated in situ by the reaction of n-BuLi and 2,2-dibromopropane.
Subject(s)
Cyclopropanes/chemical synthesis , Lithium/chemistry , Methane/analogs & derivatives , Propanols/chemistry , Cyclopropanes/chemistry , Methane/chemistry , Molecular Structure , StereoisomerismABSTRACT
A new method for the chemo- and stereoselective conversion of allylic alcohols into the corresponding cyclopropane derivatives has been developed. The cyclopropanation reaction was carried out with an unprecedented titanium carbenoid generated in situ from Nugent's reagent, manganese and methylene diiodide. The reaction involving the participation of an allylic hydroxyl group, proceeded with conservation of the alkene geometry and in a high diastereomeric excess. The scope, limitations and mechanism of this metal-catalysed reaction are discussed.
Subject(s)
Cyclopropanes/chemical synthesis , Methane/analogs & derivatives , Propanols/chemistry , Titanium/chemistry , Cyclopropanes/chemistry , Methane/chemistry , Molecular StructureABSTRACT
The synthesis of several derivatives of 3-hydroxy-2,4,8-trimethyldec-8-enolide and attempts at the synthesis of 3,4-dihydroxy-2,4,6,8-tetramethyldec-8-enolide (1), a structure which has been assigned to a metabolite of the phytopathogenic fungus, Botrytis cinerea, gave products whose spectroscopic data had significant differences from those reported for the natural product 1. The rare 11-membered lactone rings were constructed by ring-closing metathesis reactions. The increase in conformational restrictions imposed by the substituents has a high influence on the stereochemistry of the ring-closing metathesis reaction and gives rise to a decrease in the yield for the synthesis of 11-membered lactones. The predominant alkene which was obtained was the (Z)-isomer. The observed spectroscopic differences between the synthesized lactones and the natural product and the spectroscopic data of its acetylated derivative 26a allowed us to revise the structure 1 to that of the γ-butyrolactone 26.
Subject(s)
Alkenes/chemistry , Magnetic Resonance Spectroscopy , Mass Spectrometry , Molecular StructureABSTRACT
The enantioselective synthesis of (2R,3R,4E,8E)-3-hydroxy-2,4,8-trimethyldeca-4,8-dienolide (5) by ring-closing metathesis is described. This compound is an analogue of 3,4-dihydroxy-2,4,6,8-tetramethyldec-8-enolide (4) which is a rare 11-membered lactone produced by the fungus, Botrytis cinerea. Mutasynthetic studies with compound 5 using two mutants of B. cinerea led to the isolation of four new highly oxygenated 11-membered lactones (11-14) in which compound 5 has been stereoselectively epoxidized and hydroxylated at sites that were not easily accessible by classical synthetic chemistry.
Subject(s)
Botrytis/metabolism , Epoxy Compounds/metabolism , Lactones/chemical synthesis , Polyketides/chemical synthesis , Biotransformation , Botrytis/chemistry , Botrytis/genetics , Epoxy Compounds/chemistry , Hydroxylation , Lactones/chemistry , Lactones/metabolism , Molecular Structure , Mutation , Oxygen/chemistry , Polyketides/chemistry , Polyketides/metabolism , StereoisomerismABSTRACT
Two novel steroids, 3beta,7alpha-dihydroxy-4alpha,14alpha-dimethyl-5alpha-cholest-8-en-11-one (2) and 3beta,7beta-dihydroxy-4alpha,14alpha-dimethyl-5alpha-cholest-8-en-11-one (3) were isolated from the latex of Euphorbia officinarum. Their structures were established on the basis of NMR and MS studies.
Subject(s)
Cholestenones/chemistry , Cholestenones/isolation & purification , Euphorbia/chemistry , Magnetic Resonance Spectroscopy , Mass SpectrometryABSTRACT
Phytotoxic assays, performed both in vitro and in vivo on leaves of Phaseolus vulgaris, with metabolites excreted by the fungus B. cinerea are evaluated. Exogenous application of the phytotoxin botrydial has been found to produce severe chlorosis and cell collapse and facilitated fungal penetration and colonization of plant tissue. The results also show a light-dependent action mechanism for the phytotoxin and seem to indicate that botrydial is a non-host-specific toxin involved in fungal infection of B. cinerea.
Subject(s)
Botrytis/pathogenicity , Botrytis/metabolism , Phaseolus/parasitology , VirulenceABSTRACT
The sesquiterpenoid panasinsane derivatives 11 and 14-16 have been prepared from caryophyllene oxide (7). The novel rearrangement reactions of compounds 11 and 14 under TCNE-catalyzed solvolysis conditions and the reactions of compounds 15 and 16 under superacid conditions (HSO3F/Et2O, -63 degrees C) have been investigated. The ginsenol derivative 17 is obtained from compounds 11 and 14 under TCNE-catalyzed conditions. The rearrangement of compounds 15 and 16 under superacid conditions leads to the novel sesquiterpene derivatives (1S,4S,7S,10S,11S)-3,3,10,11-tetramethyltricyclo[5.3.1.0(4,10)]undecan-1,11-yl sulfate (19) and (1S,4S,5S,8S)-2,2,4,8-tetramethyl tricyclo[3.3.2.1(4,8)]undecan-11-one (20). The influence of the secondary hydroxyl group at C-5 of the panasinsane derivatives on the course of these rearrangements is discussed.
Subject(s)
Sesquiterpenes/chemistry , Sesquiterpenes/chemical synthesis , Hydrogen-Ion Concentration , Spectrum AnalysisABSTRACT
Under modified Mitsunobu reaction conditions, a novel skeleton rearrangement of terpenes has been obtained. The reactivity of 8, 9-dioxygenated isocaryolane derivatives has been investigated. When either (8R,9R)-8-methoxyisocaryolane-9-ol (7) or (8R, 9R)-isocaryolane-8,9-diol (10) are treated under acidic conditions, isocaryolan-9-one (9) and the rearrangement compound (1S,2S,5R,8S)-1, 4,4-trimethyltricyclo[6.2.1.0(2,5)]undecane-8-carbaldehyde (11) are obtained. Otherwise treatment of compounds 7 and 10 under modified Mitsunobu conditions leads to the novel sesquiterpene derivative (1S, 2S,5R,9R)-1,4,4-trimethyltricyclo[7.2.1.0(2,5)]dodecan-8-one (8). This is the first example, to our knowledge, of a Mitsunobu-induced pinacol rearrangement. The influences of the substrate and reaction conditions on the evolution of the reaction are both explored. This modification of the Mitsunobu reaction conditions introduces a new, one-pot, procedure for preparing this class of rearrangement product.
ABSTRACT
Six new sesquiterpenoid metabolites (1, 3-7) have been isolated from Botrytis cinerea. Their structures were elucidated by means of MS and extensive NMR studies. The phytotoxic activities of these new products have been evaluated.
Subject(s)
Botrytis/chemistry , Herbicides/isolation & purification , Sesquiterpenes/isolation & purification , Botrytis/metabolism , Fermentation , Herbicides/chemistry , Herbicides/toxicity , Magnetic Resonance Spectroscopy , Muscle, Smooth , Plants, Toxic , Sesquiterpenes/chemistry , Sesquiterpenes/toxicity , NicotianaABSTRACT
Biotransformation of (4E,8R)-caryophyll-4(5)-en-8-ol (1) with Botrytis cinerea afforded 14 products (3-16). Thirteen of these (4-16) are described here for the first time. The main reaction paths involved the isomerization of the double bond at C-4/C-5 and hydroxylation of methyl groups.
Subject(s)
Botrytis/metabolism , Sesquiterpenes/metabolism , Biotransformation , Molecular Structure , Sesquiterpenes/chemistry , Spectrum AnalysisABSTRACT
Biotransformation of caryophyllene oxide (1) with B. cinerea afforded 15 products (2-16). Ten of these (3-5, 7, 9-11, and 14-16) are reported here for the first time. The main reaction paths involved stereoselective epoxidation at C-8/C-13 and hydroxylation at C-7. A rearranged compound was found, which was a cyclization product 16 possessing the caryolane skeleton.
ABSTRACT
The clinical case of a 73-years old male who was admitted for diarrhea and loss of weight is presented. Barium enema and colonoscopy demonstrated small size polyps in the sigmoid colon, one of which had a histologic diagnosis of adenocarcinoma. Abdominal examination detected a mass in the mesohypogastrium which did not appear to be related to the previous findings. CAT and intestinal transit confirmed a second tumor in the small bowel with the histologic diagnosis of a resected specimen being melanoma.
Subject(s)
Adenocarcinoma , Colonic Polyps , Ileal Neoplasms , Melanoma , Neoplasms, Multiple Primary , Sigmoid Neoplasms , Adenocarcinoma/diagnostic imaging , Adenocarcinoma/surgery , Aged , Colonic Polyps/diagnostic imaging , Colonic Polyps/surgery , Follow-Up Studies , Humans , Ileal Neoplasms/diagnostic imaging , Ileal Neoplasms/surgery , Male , Melanoma/diagnostic imaging , Melanoma/surgery , Sigmoid Neoplasms/diagnostic imaging , Sigmoid Neoplasms/surgery , Time Factors , Tomography, X-Ray ComputedABSTRACT
Analog compounds of the proposed intermediates of the biogenetic pathway to botrydial have been synthesized. These compounds were tested for their potential antifungal activity against the phytopathogenBotrytis cinerea. Our results showed a fungistatic effect of some compounds on mycelium growth. The most significant effect was exerted by 2-α-hydroxy-2,3-dihydro-1-epiprobotrydial, which inhibited growth ofB. cinerea. Some aspects of structure-activity relationships are discussed.
