Alexander S. Orahovats

Intramolecular diels-alder reaction of aryl allene phosphonates

Abstract Intramolecular Diels-Alder cyclization in aryl allene phosphonatesleads only in 1c to the tricyclic 2,3-oxaphospholene 2 , 2+2 dimerization being observed in the remaining cases.

Berbin-8-ones prom 2′-halogeno-1-benzylisoquinolines and metal carbonyls

Abstract The title compounds were synthesised from 2′-halogeno-1-benzyl-isoquinolines, their 3,4-dihydro- or 1,2,3,4-tetrahydro-derivatives and metal carbonyls under mild conditions.

Photolysis and pyrolysis products of isogermacrone

Abstract The photolysis and pyrolysis of the title compound leads to, among other products, cyclobutane ring systems with crossed or parallel bonds; photolysis affords also such systems transfused to a cyclopentanone. Isogermacrone is found to be present in small amounts in the essential oil of Geranium macrorrhizum L.

2-Azetidinones from 3-aminopropanoic acids and thePh3P/CCl4(CBr4) orPh3P/Br2(I2) condensation systems

The title complexes are used as intramolecular cyclization agents to yield under mild conditions and average to good yields 2-azetidinones from variously substituted 3-aminopropanoic acids. The reaction is found to proceed in all examined cases stereospecifically, with one exception. No marked difference with respect to yields and stereospecificity is noted among the four condensation systems.ZusammenfassungDie im Titel angegebenen Systeme wurden als Cyclisationsreagentien eingesetzt, um aus substituierten 3-Aminopropansäuren 2-Azetidinone unter milden Bedingungen und mit durchschnittlichen bis guten Ausbeuten darzustellen. Mit einer Ausnahme läuft die Reaktion stereospezifisch. Bei den vier untersuchten Systemen wurde kein beträchtlicher Unterschied in bezug auf Ausbeute und Stereospezifität festgestellt.

Sesquiterpene ketones from geranium macrorrhizum

Abstract Two novel stereoisomeric tricyclic sesquiterpene ketones were isolated from Geranium macrorrhizum .

13C NMR studies on 1,7-dimethyl-4-isopropylidene-tricyclo [5.3.0.02.6] decan-3-ones (germarones) and germazone

Abstract The 13 C NMR spectra of cis-syn-cis and cis-anti-cis -1,7-dimethyl-4-isopropylidene-tricyclo[5.3.0.0 2,6 ]decan-3-ones, and their two trans -fused cyclopentanone isomers, as well as that of 1,7-dimethyl-4-isopropylidene-tricyclo-[4.4.0.0 2,7 ]decan-3-one are analysed. Chemical shifts at unusually high fields are observed for the carbonyl carbon signals of the two trans -fused cyclopentanone isomers.

A novel photochemical rearrangement of allenic esters

The alkyl allenic esters (1a–c) on irradiation are found to afford the cyclobutenones (2a–c) while the phenyl ester (1e) affords the photo-Fries product (4).