Selective tandem enyne metathesis for the synthesis of functionalized cycloheptadienes
作者:Steven T. Diver、Daniel A. Clark、Amol A. Kulkarni
DOI:10.1016/j.tet.2008.03.027
日期:2008.7
explained on the basis of a selective ringopening by the second generation Grubbs' ruthenium carbene complex. The ringopening of substituted cyclopentenes and cyclopentene contained in a bicyclic ring system was also achieved. The ring expansion of bicyclic dienes provided seven-membered dienes contained in the bicyclo[5.2.0]nonane ring system. Details of the structural analysis are also discussed. A mechanistic
important building blocks for the synthesis of biologically active molecules and can easily be accessed via Beckmannrearrangement of cyclobutanones. However, Beckmann fragmentation is often a competing reaction for these strained ketones. We found that performing the Beckmannrearrangement with Tamura’s reagent in the presence of aqueous HCl suppresses the undesired fragmentation reaction. This improved
Synthesis of (3S,4R)-eldanolide and (5S,12R)-leukotriene-B4 through photolysis of optically active hydroxy-7,7-dimethylbicyclo[3.2.0]heptanones
作者:H. Geoff Davies、Stanley M. Roberts、Basil J. Wakefield、John A. Winders
DOI:10.1039/c39850001166
日期:——
Photoisomerisation of 3-hydroxy-7,7-dimethylbicyclo[3.2.0]heptan-6-ones is the key step in a new route to the pheromone eldanolide while leukotriene-B4 is available through a photolytic retro[2 + 2] reaction of 2-hydroxy-7,7-dimethylbicyclo[3.2.0]heptan-6-ones.
Microbial oxidation of 7endo-methylbicyclo[3.2.0]hept-2-en-6-one, 7,7-dimethylbicyclo[3.2.0]hept-2-en-6-one and 2exo-bromo-3endo-hydroxy-7,7-dimethylbicyclo[3.2.0]heptan-6-one using Acinetobacter NCIMB 9871
作者:Andrew J. Carnell、Stanley M. Roberts、Vladimir Sik、Andrew J. Willetts
DOI:10.1039/p19910002385
日期:——
A bio-Baeyer–Villiger reaction using Acinetobacter NCIMB 9871 and the bicycloheptanone 2 provided the corresponding substituted oxabicyclooctanones 6 and 7. Similarly the ketones 3 and 9 furnished the lactones 8 and 10 respectively: the lactones 6, 7 and 10 were obtained in states of high optical purity.
Stereochemische Aspekte der Addition von Ketenen an Cyclopentadien
作者:M. Rey、S. Roberts、A. Dieffenbacher、A. S. Dreiding
DOI:10.1002/hlca.19700530223
日期:——
Earlier work has shown that the cyclo-addition of a ketene to a conjugated diene is always (a) 2 + 2, (b) polarily directed, and (c) suprafacial with respect to the diene CC. The adducts of ketenes and cyclopentadiene are thus always 7-substitutedbicyclo [3.2.0] hept-2-ene-6-ones. New evidence is presented to show that unsymmetrically substituted ketenes add to cyclopentadiene in such a manner that