Two routes are presented for the conversion of d-diacetone glucose (5a) into a protected carbocyclic core of BMS-200475 (Entecavir). The reduction of two terminal epoxides with Cp2TiCl to form carbon radicals and their cyclizations with a terminal acetylene and an α,β-unsaturated ester lead ultimately to allylic alcohol 11a, a candidate for Mitsunobu coupling with guanine.

(1; R = Et) [78-39-7] C8H18O3 (MW 162.26) InChI = 1S/C8H18O3/c1-5-9-8(4,10-6-2)11-7-3/h5-7H2,1-4H3 InChIKey = NDQXKKFRNOPRDW-UHFFFAOYSA-N (2; R = Me) [1445-45-0] C5H12O3 (MW 120.17) InChI = 1S/C5H12O3/c1-5(6-2,7-3)8-4/h1-4H3 InChIKey = HDPNBNXLBDFELL-UHFFFAOYSA-N (diethyl acetal of ethyl acetate; provides γ,δ-unsaturated ethyl esters from α,β-unsaturated alcohols through the Claisen rearrangement; converts diols to epoxides of the same relative stereochemistry; gives 2-methyl-1,3-heteroatom ring systems) Physical Data: (1) bp 144–146 °C; d = 0.8847 g cm−3; (2) bp 107–109 °C; d = 0.9438 g cm−3.

Studies directed toward a synthesis of the sesquiterpene FS-2 have permitted an investigation of the fragmentation of a cyclobutylcarbinyl radical that preferentially cleaves to give the more stable of two possible radicals. This observation is contrasted with the results obtained in an analogous cyclobutyloxy radical fragmentation.

[GRAPHICS]A facile fragmentation of beta -alkyl-beta -aryl-alpha -oxo-gamma -butyrolactones is reported. A study to assist in the elucidation of the mechanism of the reaction is also revealed.

D-Xylose serves as a starting material for approaches to the synthesis of the glucosidase inhibitors, (+)-cyclophellitol (1) and (+)-epi-cyclophellitol (2). An investigation of the cyclization of diastereomeric oxiranyl radicals to achieve this goal was moderately successful with the diastereomer that would have led to epi-cyclophellitol undergoing cyclization. An alternative route to cyclophellitol from D-xylose employed Grubbs' ring closure metathesis and radical transformations to complete the synthesis.

A synthesis of (+)-desmethoxymitomycin A is described. The critical step is a highly stereoselective cyclization of an aziridinyl radical to afford a tetracycle having the same relative and absolute stereochemistry as mitomycin A and C.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An asymmetric route to the core nucleus of the antitumor agent FR-900482 utilizes the cyclization of an aziridinyl radical into a functionalized indole nucleus. The route employs a selective Polonovski reaction and the Hootele-Dmitrienko rearrangement to install two oxygen atoms.

A tandem radical fragmentation of a cyclopropylcarbinyl/oxiranylcarbinyl system leads to the PGB(1) series of prostaglandins. Control of cyclopropane bond fragmentation as a function of C-2 substitution in bicyclo[3.1.0]hexanylcarbinyl radicals is presented.

Substituted oxiranyl radicals have been generated from glycidic acids. The cyclization of these species, the stereochemistry of the resultant products, and an intermolecular application of these reactive species is considered.

A carbon-centered aziridinyl radical has been generated from the ester of chiral aziridine carboxylic acid 5b. The resultant radical has been cyclized directly and has been brominated with CBrCl3. The bromo aziridines have also been cyclized reductively in the presence of n-Bu(3)SnH. Dihydroindole 8b bears the same relative and absolute stereochemistry as the mitomycin C nucleus.

The total syntheses of (+/-)-scopadulcic acids A (1) and B (2a) and (+/-)-scopadulciol (2b) from the late, common intermediate 3 are described. The route provides a chemical correlation of the structures of the three natural products.

A radical cyclization is employed in the synthesis of a biosynthetic precursor of aristeromycin and neplanocin A. A derivative of L-tartaric acid is used as both the source of chirality and the carbon radical.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAllyloxy Radicals are Formed Reversibly from Oxiranylcarbinyl Radicals: A Kinetic StudyFrederick E. Ziegler and Anders K. PetersenCite this: J. Org. Chem. 1995, 60, 9, 2666–2667Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 May 1995https://pubs.acs.org/doi/10.1021/jo00114a011https://doi.org/10.1021/jo00114a011research-articleACS PublicationsRequest reuse permissionsArticle Views169Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

The tandem radical fragmentation of four stereoisomeric epoxy thiocarbonates 7c-10c has been investigated. In each instance a cyclopropylcarbinyl radical fragments to generate an oxiranylcarbinyl radical, which, in turn, undergoes fragmentation. The Initially detected product is (Z)-allylic alcohol 23, which isomerizes to (E)-allylic alcohol 24 under acid catalysis. The reversibility of allyloxyl radical formation is considered.