Showing papers on "Enone published in 1971"

Chemistry of the Podocarpaceae. XXVII. Ring-c modifications of methyl abieta-8,11,13-trien-18-oate

Abstract: Functionalization of the isopropyl group of methyl abieta-8,11,13- trien-18-oate (8) has been achieved by intramolecular cyclizations of the 12-carboxy derivative (10) with lead tetraacetate and by thermolysis of the diazomethyl ketone (11). Nitration of methyl 12-acetylabieta-8,11,13-trien-18-oate (9) has given the products (21) and (30), arising from nitrodeacylation and nitrodealkylation reactions, respectively. The nitro ketone (30) has been converted into methyl 13-hydroxypodocarpa-8,11,13-trien-18-oate (38) in 26% overall yield from the ester (8). Birch reduction of the methyl ether of the phenol (38) afforded the enone (50), a potentially useful intermediate for synthesis.

Photochemische Reaktionen. 65.(vorläufige) Mitteilung. Spezifisch π → π*‐induzierte Photoisomerisierungen von 10‐Dimethoxymethyl‐Δ1,9‐octal‐2‐on. Ein photochemischer Zugang zu [4.4.3]‐12‐Oxapropellan‐Derivaten

Abstract: Selective n π* excitation of the α,β-unsaturated enone 1 in hydrocarbon solvents resulted in a deconjugation reaction to 3, reminiscent of results previously reported for similar systems [2], whereas the photoreactivity of 1 in alcohol solvents at wavelengths >3400 A was so small that only product 4 has been identified as yet. Excitation of the π π* transition of compound 1 at 2537 A initiated additional phototransformations which could not be effected by irradiation in the first absorption band. The [4.4.3]-12-oxapropellane derivative 2 was identified as one of the two new major photo-isomers. A 6:8 mixture of products 2 and 3, plus about 1 part of an isomer of still unknown structure (see however, the Addendum), were readily formed in hydrocarbon solvents, and a 1:10 ratio of 2 and the unknown product was obtained in methanol. Abstraction of a methoxyl hydrogen by the ketone oxygen is proposed to account for the primary photochemical step in the cyclization to 2. A hydrogen-deuterium isotope effect of 2.7 was observed in a competitive experiment using 1 and 1-d6. 34% of one deuterium atom were exchanged for hydrogen when 1-d6 was photolyzed to 2-d6 in t-butyl alcohol, which suggests an intermediate of type a in the pathway 1 2 possessing a readily exchangeable proton. Steric considerations would require a strongly distorted, non-planar excited-state geometry of the enone group of 1 for the oxygen to approach a methoxyl hydrogen. The transformation 1 2 represents a novel reaction type in photochemical processes of conjugated enones which are specifically induced by π π* excitation only.

Reaction products from αβ-unsaturated ketones and aliphatic diamines or dithiols

Abstract: Ethylenediamine reacts with αβ-unsaturated ketones to give either tetrahydrodiazepines, tetra-azacyclotetra-decadienes, or uncyclised adducts derived from one molar equivalent of amine and two of enone. 1,3-Diaminopropane gave either a hexahydrodiazocine or an uncyclised adduct. 1,6-Diaminohexane, piperazine, or ethane-1,2-dithiol gave only uncyclised adducts. Some reactions of the uncyclised adducts are mentioned.

Dibenzo(a-d)cycloheptadi(or tri)ene-5:2'-dioxalanes(i,3')

Abstract: A COMPOUND OF THE FORMULA Z<(-(1,2-PHENYLENE)-C<(-O-CH2-C(-CH2-N(-R)(-R''))-O-)-(1,2- PHENYLENE)-) IN WHICH Z IS -CH2-CH2- OR -CH=CH-, AND R AND R'' EACH IS AN ALKYL 1-3C OR -N(-R)-R'' IS PYRROLIDINO, PIPERIDINO, HEXAMETHYLENEIMINO OR MORPHOLINO. THE COMPOUNDS ARE PREPARED BY CONDENSING, IN THE PRESENCE OF STANNIC CHLORIDE IN CHLOROFORM OR CARBON TETRACHLORIDE, AN EPIBROMOHYDRIN WITH DIBENZO (A-D) CYCLOHEPTADI (OR TRI) ENONE. THIS INTERMEDIATE IS THEN CONDENSED, IN BENZENE WITH A SECONDARY AMINE TO OBTAIN THE COMPOUND. THE COMPOUNDS POSSESSES ANALGESIC, SEDATIVE, ANTHISTAMINIC, ANTI-SEROTONENIC, ANTI-INFLAMMATORY, ANTICONVULSANT AND ANTI-DEPRESSANT PROPERTIES.

Dehydration of 4-hydroxy-2,3,4-triphenylcyclopent-2-enone

Abstract: Dehydration of the title alcohol with toluene p-sulphonic acid in benzene yields a yellow dimer identified as trans-2,2′-dioxo-3,3′,4,4′,5α,5′β-hexaphenyl-1,1′-bi(cyclopentenylidene)(IV). Irradiation in sunlight causes isomerisation about the central double bond and the cis-isomer obtained (IX) is thermally reconverted into the trans at 185°. A second dimer isolated from the same reaction is formulated as 2,3,3a,5,6-pentaphenyl-3a,3b,6a,10b-tetrahydrobenz[e]-as-indacene-1,4-dione (XIII). Dehydration of the title alcohol with acetic acid–sulphuric acid yields a blue dehydro-dimer, 3-hydroxy-1,2,5,6,10b-pentaphenyldihydrobenz[e]-as-indacen-4-one (XIV), whose allyl ether undergoes a Claisen rearrangement and an internal Diels–Alder addition. The mass spectra of two dimethoxylated analogues (XXIX) and (XXX) are discussed.

Photochemistry of the extended conjugated system 3-oxoprop-1-enylcyclopropane of the diterpene, epoxylathyrol

Abstract: The extended conjugated system of epoxylathyrol can be quantitatively isomerised by light to the cis, non-planar, enone (7), and thence to the fragmentation product (3), a furan.

The photo-addition of 3-phenylcyclohex-2-enone and tetramethylethylene. Evidence for singlet and triplet pathways leading to a common intermediate

Abstract: The photo-addition of 3-phenylcyclohex-2-enone and tetramethylethylene occurs from S1 on direct irradiation, and from T1 on sensitization, to afford the same cyclobutane adduct.

Some aspects of terpenoid chemistry

Abstract: The chemotaxonomy and the biosynthesis of tetranortriterpenes is briefly reviewed in chapter one and the partial syntheses of some of these products is described. The work described in the first part of chapter two was directed towards a synthesis of the andgamma;-lactone ring system in the side chain of flindissol, while that in the latter part involved studies of the allylic oxidation in ring D of some apotirucallol derivatives. The acid constituents of Manila elemi resin were separated and methyl 3andalpha;-acetoxytirucalla-8,24-dien-21-oate (1) was then converted to 3andbeta;-acetoxytirucall-8,24-dien-21-oic acid. Bromination of this acid resulted in low yields of the dibromide and an explanation for this was put forward. The action of ammonia on the acyl chloride of 3andalpha;-acetoxytirucalla-8,24-dien-21-oic acid followed by reaction with lead tetra-acetate and iodine led to formation of 3andalpha;-acetoxy(21-24)cyclotirucalla-7,9(11),24-trien-21-one. Reaction of 3andalpha;-acetoxytirucall-8-en-21-amide with lead tetra-acetate and iodine resulted in formation of 3andalpha;-acetoxytirucalla-7,9(11)-dien-21-isocyanate and explanations for these results are given. Ozonolysis was used extensively during this work and the mechanism of ozonolysis is discussed. Treatment of a mixture of methyl 3andalpha;-acetoxytirucall-7 and 8-en-21-oate with ozone gave three products, methyl 3andalpha;-acetoxy-7andalpha;,8andalpha;-epoxytirucallan-21-oate (2), methyl 3andalpha;-acetoxy-7-oxotirucall-8-en-21-oate and methyl 3andalpha;-acetoxy-7,11-dioxotirucall-8-en-21-oate. The 7andalpha;,8andalpha;-epoxide (2) was rearranged with boron trifluoride and acetylation of the product gave methyl 3andalpha;,7andalpha;-diacetoxyapotirucall-14-en-21-oate (3). A crude mixture of dibromo elemi acid methyl esters was ozonised and reductive work up gave four products, (13andalpha;H)ursan-3,12-dione, methyl 3,7-dioxotirucalla-8,24-dien-21-oate, methyl 3,7, 11-trioxotirucalla-8,24-dien-21-oate and methyl 7andalpha;-bromo-3,15-dioxo-(14andalpha;H)apotirucall-24-en-21-oate (4). Similarly ozonolysis of a crude mixture of methyl 3andalpha;-acetoxy-24,25-dibromo-tirucall-7 and 8-en-21-oate and reductive work up gave a mixture of seven products. Methyl 3andbeta;-acetoxy-12-oxo-(13andbeta;H)ursan-28-oate, methyl 3andalpha;-acetoxy-7andalpha;,8andalpha;-epoxytirucall-24-en-21-oate (5), methyl 3andalpha;-acetoxy-7andalpha;-bromo-15-oxo-(14andalpha;H)apotirucall-24-en-21-oate (6), methyl 3andbeta;-acetoxy-11-oxours-12-en-28-oate (7), methyl 3andalpha;-acetoxy-7,11-dioxotirucalla-8,24-dien-21-oate, methyl 3andalpha;-acetoxy-7-oxotirucalla-8,24-dien-21-oate and methyl 3andalpha;-acetoxy-14andbeta;,15andbeta;-epoxy-7andalpha;-hydroxyapotirucall-24-en-21-oate (8). The structure and mechanism of formation of (7) and (8) is discussed. The crude 7andalpha;,8andalpha;-epoxide (5) was rearranged with boron trifluoride and acetylation of the product gave methyl 3andalpha;,7andalpha;-diacetoxyapotirucalla-14,24-dien-21-oate (9). The structure and mechanism of formation of the two 7andalpha;-bromides (4) and (6) is discussed. Reaction of methyl 3andalpha;-acetoxy-24,25-dibromotirucall-8-en-21-oate with tetramethylammonium acetate gave methyl 3andalpha;-acetoxy-24-bromotirucalla-8,24-dien-21-oate which was reduced to 24-bromotirucalla-8,24-dien-3andalpha;,21-diol and reduction of this diol gave tirucall-8-en-3andalpha;,21-diol. Oxidation of (1) with iodine and iodic acid in aqueous dioxan and acetylation of the products gave methyl 3andalpha;-acetoxy-24andxi;,25-epoxytirucall-8-en-21-oate and methyl 3andalpha;,24andxi;-diacetoxy-25-hydroxytirucall-8-en-21-oate which was hydrolysed to methyl 3andalpha;,24,25-trihydroxytirucall-8-en-21-oate. Bromination of (9) gave methyl 3andalpha;,7andalpha;-diacetoxy-24,25-dibromoapotirucall-14-en-21-oate (10) in 38% yield. Oxidation of this dibromide with selenium dioxide gave what is thought to be the 14,15-diol and the mechanism of oxidation with selenium dioxide is discussed. Treatment of (3) with bispyridinechromium oxide and also with aqueous N-bromosuccinimide gave methyl 3andalpha;,7andalpha;-diacetoxy-16-oxoapotirucall-14-en-21-oate in good yield. Similarly oxidation of (10) with bispyridinechromium oxide gave the 14-en-16-one in good yield but after denomination, methyl 3andalpha;,7andalpha;-diacetoxy-16-oxoapotirucall-14,24-dien-21-oate decomposed on attempted purification. Deoxygenation of havanensin triacetate with a zinc-copper couple deoxyhavanensin triacetate in good yield but attempts to oxidise this alkene with either selenium dioxide or bispyridinechromium oxide were unsuccessful. Oxidation of this alkene with aqueous chromic acid gave isophotodeoxyhavanensin triacetate. The literature of the chemistry of some pentacyclic triterpene-12-ketones is discussed in chapter three together with the structures of some new 12-ones and their o.r.d. curves and mass spectra. The triterpene lupeol was used as a model system to construct the 1andalpha;,3andalpha;-diacerate group common to the meliacins and this work is described in chapter four. Lupeol benzoate was firstly converted to lupan-3-one. Treatment of lupan-3-one hydrazone with lead tetra-acetate gave 5(4andrarr;3)-abeolup-3-ene and the mechanism of this reaction is discussed. Bromination of lupan-3-one gave a mixture of 2(andalpha; and andbeta;)-bromolupan-3-ones which was dehydrobrominated to lup-1-en-3-one. Epoxidation of this enone with hydrogen peroxide gave 1andalpha;,2andalpha;-epoxylupan-3-one which on rearrangement with hydrazine gave lup-2-en-1andalpha;-ol. Epoxidation of this alcohol gave 2andalpha;,3andalpha;-epoxylupan-1andalpha;-ol which was reduced with lithium in ethylamine to lupan-1andalpha;,3andalpha;-diol. The yield of this diol was greater by this route than by reduction of 1andalpha;,2andalpha;-epoxylupan-3-one. The o.r.d. of some lupan-3-ones is also discussed. The structure of a new diterpene furan and an attempt to synthesise this product from sclareol is described in chapter five. Oxidation of sclareol with chromic acid in acetic acid gave norambreinolide and 8andalpha;-acetoxy-13,14,15,16-tetranorlabdan-12-oic acid. Methanolysis of norambreinolide gave a 1:1 mixture of starting material and methyl 8andalpha;-hydroxy-13,14,15,16-tetranorlabdan-12-oate and a synthetic route via this ester was not pursued. Reduction of norambreinolide gave 13,14,15,16-tetranorlabdan-8andalpha;,12-diol which gave 8andalpha;-acetoxy-13,14,15,16-tetranorlabdan-12-yl acetate on acetylation. Dehydration of this acetate with phosphoryl chloride gave a mixture of 13,14,15,16-tetranorlabd-7 and 8(17)-en-12-yl acetates. Hydrolysis of this mixture and oxidation of the alcohols with silver carbonate gave a mixture of 13,14,15,16-tetranorlabd-7 and 8(17)-en-12-als. Reformatsky condensation of these aldehydes with ethyl andalpha;-bromoacetate gave a mixture of ethyl 12-hydroxy-15,16-dinorlabd-7 and 8(17)-en-14-oates. Treatment of this mixture of hydroxyesters with o-monoperphthalic acid gave pure ethyl 12andxi;-hydroxy-15,16-dinorlabd-8(17)-en-14-oate, together with ethyl 7andalpha;, 8andalpha;-epoxy-12andxi;-hydroxy-15,16-dinorlabdan-14-oate. The C-12 epimers of these products were separated and their spectra and the configuration of these epimers at C-12 is discussed. Oxidation of ethyl 12andxi;-hydroxy-15,16-dinorlabd-8(17)-en-14-oate gave ethyl 12-oxo-15,16-dinorlabd-8(17)-en-14-oate. Reaction of this andbeta;-keto-ester with 1,2-dichloroethyl ethyl ether and aqueous sodium hydroxide gave only traces of a furan while in triethylamine, a mixture of products was obtained. From these results it was concluded that a different approach to synthesis of the furan ring may be necessary.