Preparation and thermal rearrangement of trans-3-[1-methyl-2-(2-methyl-1-propenyl)cyclopropyl]-2-cyclohexen-1-one. A synthesis of (±)-[β-himachalene

1983 ◽  
Vol 61 (6) ◽  
pp. 1239-1247 ◽  
Author(s):  
Edward Piers ◽  
Edward H. Ruediger
Keyword(s):  
Total Synthesis ◽  
Wittig Reaction ◽  
Phase Transfer ◽  
Aqueous Sodium Hydroxide ◽  
Butyl Alcohol ◽  
High Yield ◽  
Thermal Rearrangement ◽  
Aqueous Sodium ◽  
Tert Butyl Alcohol ◽  
Enol Phosphate

A total synthesis of the sesquiterpenoid (±)-β-himachalene (2) is described. Treatment of 5,5-dimethyl-2-vinyl-1,3-dioxane (24) with bromoform and aqueous sodium hydroxide in the presence of a phase-transfer catalyst afforded the dibromocyclopropane 25. When the latter substance was allowed to react (tetrahydrofuran–hexamethylphosphoramide, −95 °C) with n-butyllithium in the presence of methyl iodide, a mixture of the epimeric products 26 (87–93%) and 27 (7–13%) was produced in high yield. Compound 26 was converted via a two-step sequence (hydrolysis with 88% formic acid, 26 → 28; Wittig reaction with isopropylidenetriphenylphosphorane, 28 → 16) into the bromocyclopropane 16, which was transformed into the cuprate reagent 17. Reaction of 3-iodo-2-cyclohexen-1-one (4) with reagent 17, followed by thermolysis (xylene, reflux) of the resultant product 18 (the title compound), afforded, in quantitative yield, the dienone 12. Methylation of 12 furnished compound 29 which, upon hydrogenation in the presence of tris(triphenylphosphine)chlororhodium, gave the ketone 32. Conversion of compound 32 into the corresponding enol phosphate 33, followed by reduction (lithium, ethylamine–tetrahydrofuran, tert-butyl alcohol) of the latter material, provided (±)-β-himachalene (2).

Total synthesis of tetracyclic sesquiterpenoids: (±)-ishwarone

1980 ◽  
Vol 58 (23) ◽  
pp. 2613-2623 ◽  
Author(s):  
Edward Piers ◽  
Tse-Wai Hall
Keyword(s):  
Total Synthesis ◽  
Phase Transfer ◽  
Aqueous Sodium Hydroxide ◽  
Pyridinium Chlorochromate ◽  
Aqueous Sodium ◽  
Standard Methodology ◽  
Propargylic Alcohol ◽  
Crude Product ◽  
Hexamethyl Phosphoramide ◽  
Hydrolysis Of

A stereoselective total synthesis of the racemic modification of the tetracyclic sesquiterpenoid ishwarone (2) is described. Treatment of the known ketal aldehyde 19 with dibromomethylenetriphenylphosphorane gave the dibromo alkene 20, which was transformed efficiently into the propargylic alcohol 21. The latter compound was converted via the intermediates 22–24 into the octalone 12, which in turn was transformed by standard methodology into the corresponding ketal 7. Treatment of 7 with bromoform–aqueous sodium hydroxide in the presence of a phase-transfer catalyst, followed by acid hydrolysis of the resultant crude product, gave the crystalline keto dibromide 27. When a solution of the corresponding ketal 26 in tetrahydrofuran–hexamethyl-phosphoramide containing methyl iodide was treated with tert-butyllithium, the monobromo ketals 28 (58%) and 29 (38%) were formed. Compound 28 was converted by means of conventional reactions into the keto alcohol 32. Attempts to transform the latter substance into (±)-ishwarone (2) proved unsuccessful. When the olefinic ketal 7 was allowed to react with dimethyl diazomalonate in the presence of copper bronze, the diester 44 was produced in good yield. The latter intermediate was converted via standard methodology into the keto dimesylate 47 which, upon reaction with lithium chloride in ether–hexamethylphosphoramide, gave the corresponding dichloride 48. Treatment of 48 with potassium tert-butoxide in tetrahydrofuran resulted in an intramolecular alkylation to provide the tetracyclic keto chloride 50. Reduction of 50 with lithium triethylborohydride in tetrahydrofuran afforded (±)-ishwarol (51) which, upon oxidation with pyridinium chlorochromate in dichloromethane, furnished (±)-ishwarone (2).

The use of polymer supports in organic synthesis. VIII. Solid phase syntheses of insect sex attractants

1977 ◽  
Vol 55 (7) ◽  
pp. 1143-1153 ◽  
Author(s):  
Clifford C. Leznoff ◽  
Thomas M. Fyles ◽  
J. Weatherston
Keyword(s):  
Trichoplusia Ni ◽  
Solid Phase ◽  
Butyl Alcohol ◽  
High Yield ◽  
Argyrotaenia Velutinana ◽  
Sex Attractants ◽  
Polymer Supports ◽  
Insect Sex Attractants ◽  
Tert Butyl Alcohol ◽  
Insect Sex

A 2% cross-linked divinylbenzene–styrene copolymer, incorporating trityl chloride groups, (1), was used in the synthesis of insect sex attractants of Lepidoptera by two independent routes. Polymer 1 reacted with the symmetrical diols 1,6-hexanediol, 1,8-octanediol, and 1,10-decanediol to give the monoblocked polymer-bound diols 5–7, respectively. Mesylation of 5–7 gave the polymer-bound monomesylates 8–10, which on coupling with 1-lithio-1-hexyne or 1-lithio-1-butyne gave the polymer-bound alkyne trityl ethers 18–20. Alkynols, obtained by hydrolysis from polymers 18-20, were selectively reduced and acetylated to give cis-7-dodecen-1-ol acetate (28), cis-9-tetradecen-1-ol acetate (29), and cis-11-tetradecen-1-ol acetate (30), the sex attractants of Trichoplusia ni (Hübner), Spodoptera frugiperda (J. E. Smith), and Argyrotaenia velutinana (Walker), respectively. Alternatively, polymer-bound 1,7-heptanediol (33), polymer-bound 1,9-nonanediol (34), and 7 were oxidized with the Sharpless reagent (CrO2Cl2/tert-butyl alcohol/pyridine) to give polymer-bound aldehydes 35–37, which on reaction with Wittig reagents and subsequent hydrolysis and acetylation gave 28, 29, and 10-tetradecen-1-ol acetate (47), the sex attractant of Archips semiferanus (Walker). A 'reverse' Wittig synthesis of 47 was achieved by the reaction of polymer 10 with molten triphenylphosphine followed by base and treatment with butyraldehyde. Subsequent cleavage and acetylation gave 47 in high yield and stereoselectivity containing greater than 91% of the cis isomer.

A Total Synthesis of Dimethyl 2,3-O-Isopropylidene-l-O-oxalyl-β-DL-ribo-hexofuran-5-ulosuronate

1975 ◽  
Vol 53 (18) ◽  
pp. 2701-2706 ◽  
Author(s):  
George Just ◽  
Karl Grozinger
Keyword(s):  
Total Synthesis ◽  
Title Compound ◽  
Catalytic Reduction ◽  
Major Product ◽  
Diels Alder ◽  
High Yield ◽  
Thermal Rearrangement ◽  
Dimethyl Acetylenedicarboxylate ◽  
Alder Adduct

The synthesis of the title compound 5 was accomplished by a high-yield thermal rearrangement of the ozonide (3) of dimethyl 5,6-O-isopropylidene-7-oxabicyclo[2.2.1]hept-2-ene-exo-5,6-diol-2,3-dicarboxylate (2a), which is obtained in 30% yield from the Diels–Alder adduct of furan and dimethyl acetylenedicarboxylate. Catalytic reduction of 5 gave methyl 2,3-O-iso-propylidene-β-DL-talofuranuronate (8) as the major product, accompanied by a small amount of the allo isomer 9.

CYCLOHEXANE COMPOUNDS: V. THE REACTION OF 1-METHOXYCYCLOHEXENE-2 WITH AQUEOUS N-BROMOSUCCINIMIDE. THE 1-METHOXY-2-BROMO-3-HYDROXYCYCLOHEXANES

1965 ◽  
Vol 43 (8) ◽  
pp. 2398-2407 ◽  
Author(s):  
R. A. B. Bannard ◽  
A. A. Casselman ◽  
L. R. Hawkins
Keyword(s):  
Sodium Hydroxide ◽  
Vapor Phase ◽  
Hydrobromic Acid ◽  
Aqueous Sodium Hydroxide ◽  
Product Distribution ◽  
High Yield ◽  
Aqueous Sodium ◽  
Authentic Specimen ◽  
Steric Factors

Interaction of 1-methoxycyclohexene-2 and aqueous N-bromosuccinimide gave a mixture of stereoisomeric bromohydrins, which, on treatment with aqueous sodium hydroxide, furnished 1β-methoxy-2α,3α-epoxycyclohexane (I) and 1α-methoxy-2α,3α-epoxycyclohexane (II) in the ratio 3:1. The mixture from the N-haloimide-olefin reaction was separated by preparative vapor phase chromatography into three isomeric bromohydrins, 1α-methoxy-2α-hydroxy-3β-bromocyclohexane (IV), 1α-methoxy-2α-bromo-3β-hydroxycyclohexane (V), and 1α-methoxy-2β-bromo-3α-hydroxycyclohexane (VI) in the relative proportions 1:10:4. The 3-bromo isomer IV was identified by comparison with an authentic specimen prepared by the action of hydrobromic acid on the oxide II. Compounds V and VI were shown to have the indicated structures by deetherification to the corresponding bromodiols VII and VIII in high yield, followed by debromination of the latter to trans- and cis-1,3-cyclohexanediol respectively. The product distribution is considered in relation to the intervention of electronic and steric factors in a possible mechanism suggested for the reaction between aqueous N-bromosuccinimide and 1-methoxycyclohexene-2.

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