The use of a combination of amine–borane complexes and soluble palladium catalyst allows the fast deprotection of allyl carbamates under near-to-neutral conditions and without any side-formation of allylamine. Preliminary experiments indicate that palladium catalyst–amine–borane systems seem ideally suited for removal of Nα-Alloc terminal groups during solid phase peptide synthesis according to the N α-Alloc temporary protection strategy.

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Kinetic data and activation parameters are reported for the thermal rearrangement of seven 5-methoxy-2-aryl-1,3,4-oxadiazoles and three 5-ethoxy-2-aryl-1,3,4-oxadiazoles 3 in the melt. This reaction is a model for the thermal, uncatalyzed, 1,3-rearrangement of alkyl-imidates into N-alkyl amides. The rate law In (1 + root 1 - (1 - alpha)(2)/1 - alpha = k(obs) t, deduced from a plausible double ionic chain mechanism, is well obeyed up to 50-70% completion. In the case of 5-methoxy derivatives, a statistical analysis of experimental results demonstrates the existence of two different isokinetic relationships, corresponding to the same isokinetic temperature. Correlation between the activation energy and the sigma(alpha) and sigma(F) Taft parameters divides compounds 3 into the same two groups : compounds with X = H, OCH3, CN, NO2 are more reactive than those with X = F, CI, Br. Kinetic constants for the analogous rearrangement of 5-ethoxy derivatives confirms that this rearrangement occurs via a S(N)2 mechanism.

AbstractIn einem Zeitraum von mehr als zwei Jahren lagem sich die Oxadiazole (I) in die Oxoverbindungen (II) um.

Chemischer InformationsdienstVolume 17, Issue 18 Physical Organic Chemistry ChemInform Abstract: Alkylation of Ambident Anions Derived from 2-Aryl-1,3,4-oxadiazol- 5(4H)-ones. M. DESSOLIN, M. DESSOLINSearch for more papers by this authorM. GOLFIER, M. GOLFIERSearch for more papers by this authorT. PRANGE, T. PRANGESearch for more papers by this author M. DESSOLIN, M. DESSOLINSearch for more papers by this authorM. GOLFIER, M. GOLFIERSearch for more papers by this authorT. PRANGE, T. PRANGESearch for more papers by this author First published: May 6, 1986 https://doi.org/10.1002/chin.198618080AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume17, Issue18May 6, 1986 RelatedInformation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAlkylation of ambident anions derived from 2-aryl-1,3,4-oxadiazol-(4H)-ones. 1. Crystal structures of the silver and rubidium salts of 2-phenyl-1,3,4-oxadiazol-(4H)-oneMichele Dessolin, Michel Golfier, and Thierry PrangeCite this: J. Org. Chem. 1985, 50, 23, 4461–4465Publication Date (Print):November 1, 1985Publication History Published online1 May 2002Published inissue 1 November 1985https://pubs.acs.org/doi/10.1021/jo00223a009https://doi.org/10.1021/jo00223a009research-articleACS PublicationsRequest reuse permissionsArticle Views53Altmetric-Citations6LEARN 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 (1)»Supporting Information Supporting Information Get e-Alerts

AbstractThe assignment of all ring carbons of 37 derivatives of 1,3,4‐oxa‐ or thiadiazoles and of seven isosydnones is described. In some cases, 13C‐labelled compounds were used. The analysis of substituent effects and the calculation of charge densities of some of the derivatives suggest that the two nitrogen atoms form a protective screen against electron perturbation and play the role of an ‘electronic buffer’. A notable variation of chemical shifts could be observed only when oxygen is replaced by sulphur.