Five-membered Carbocycles Research Articles

Selective reduction of alkynes by the reagent Sml 2 - Transition metal catalysts - proton donors

Alkynes were selectively reduced to cis-olefins under mild conditions by Sml 2 in admixture with first-row transition metal catalysts and appropriate proton donors, in which the corresponding transition metal hydrides are presumed as the reactive species. The conditions also effected the conversion of 1,6-diynes to the corresponding five-membered carbocycles.

Stereospecific preparation of polyfunctional olefins by the carbometalation of alkynes with polyfunctional zinc-copper organometallics. Stereospecific preparation of five-membered carbocycles by intramolecular carbocupration

The addition of copper reagents prepared by transmetalation from polyfunctional organozinc iodides to reactive alkynes such as 1-(methylthio)-1-hexyne, phenylacetylene and acetylene, leads to stereochemically well-defined (syn addition), highly functionalized alkenylcopper reagents that after protonation, allylation, iodolysis, or stannylation afford stereochemically pure di-, tri-, and tetrasubstituted olefins. A similar intramolecular carbocupration has allowed the preparation of highly substituted five-membered carbocycles. Compared to lithium-or magnesium-copper reagents, the highly functionalized copper reagents can contain an ester, nitrile, or chloride function. However, they display a lower reactivity than the lithium- or magnesium-copper reagents and do not react with unactivated terminal alkynes

ChemInform Abstract: Stereochemistry. Part 78. A New Diastereoselective (3 + 2)Annulation Approach to Five‐Membered Carbocycles.

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.

Radical cyclisation of some 1,2,6-trideoxy-3,4-di- O-benzyl-6-halogeno- [formula omitted]- arabino-hex-1-ynitol derivatives

Free radical cyclisation of the title halides 5a, 5b, 5c and 16 led to five-membered carbocycles in good yield. The main products are two isomeric deoxy compounds resulting from the extrusion of benzaldehyde. A three-step process [5-exo-digcyclisation, 1,5 hydrogen-atom-transfer, fragmentation] is proposed to explain their formation.

ChemInform Abstract: Stereoselective Cyclic Carbolithiation of Alkyne Derivatives. A Stereoselective Synthesis of Exocyclic Alkenes.

Abstract (Trimethylsilyl)alkyne derivatives that are lithiated in the δ position via non-radical routes can cyclize in a stereoselective manner (≥96-98%) to give exocyclic alkenes containing five-membered carbocycles in high yields.

Stereoselective cyclic carbolithiation of alkyne derivatives. A stereoselective synthesis of exocyclic alkenes

(Trimethylsilyl)alkyne derivatives that are lithiated in the δ position via non-radical routes can cyclize in a stereoselective manner (≥96-98%) to give exocyclic alkenes containing five-membered carbocycles in high yields.

A new diastereoselective 3+2 annulation approach to five-membered carbocycles.

The newly prepared 1-bromo-2-methylene-3-phenylsulfonylpropane 2 reacts with α,β unsaturated esters in a Michael induced ring closure to provide cyclopentane derivatives with complete diastereoselectivity.

ChemInform Abstract: A New Transformation of Aldose Derived Synthons to Pseudo‐Hexopyranose or Pseudo‐Pentofuranose Derivatives.

ChemInformVolume 18, Issue 2 Natural Products ChemInform Abstract: A New Transformation of Aldose Derived Synthons to Pseudo-Hexopyranose or Pseudo-Pentofuranose Derivatives. K. TADANO, K. TADANO Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorH. MAEDA, H. MAEDA Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorM. HOSHINO, M. HOSHINO Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorY. IIMURA, Y. IIMURA Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorT. SUAMI, T. SUAMI Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this author K. TADANO, K. TADANO Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorH. MAEDA, H. MAEDA Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorM. HOSHINO, M. HOSHINO Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorY. IIMURA, Y. IIMURA Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this authorT. SUAMI, T. SUAMI Dep. Appl. Chem., Fac. Sci. Technol., Keio Univ., Kohoku, Yokohama 223, JapanSearch for more papers by this author First published: January 13, 1987 https://doi.org/10.1002/chin.198702323AboutPDF 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. Volume18, Issue2January 13, 1987 RelatedInformation

A NEW TRANSFORMATION OF ALDOSE DERIVED SYNTHONS TO PSEUDO-HEXOPYRANOSE OR PSEUDO-PENTOFURANOSE DERIVATIVES

Abstract The d-ribose or d-erythrose derived acyclic synthon, which possesses a 2-malonyl carbon chain at C-1 position, was cyclized stereoselectively to a six- or five-membered carbocycle. Those carbocycles were converted into pseudo-β-l-mannopyranose derivatives or pseudo-β-l-arabinofuranose derivatives efficeintly.

A new method for synthesis of five-membered carbocycles: use of the ester enolate rearrangement in conjunction with radical cyclization

4-(Phenylseleno)butyryl esters (2), easily prepared from allylic alcohols, are convertible into cyclopentanes by successive ester enolate rearrangement (2)→(3) and 5-exo-trigonal radical cyclization (4)→(6); this general process is efficient and the stereochemical result is predictable.

Radical annulation: a method for preparation of carbocycles

β-Acetylenic radicals, e.g., (6b) and (12), generated in three steps from epoxides or in two steps from α-halogenoketones, respectively, react with electron-deficient olefins to produce five-membered carbocycles by a process of conjugate addition and 5-exo-digonal closure.

Intramolecular sulfur-ylide additions to ketones. A cyclopentane annulation1

Various 2-(3′-phenylthiopropyl)cycloalkanones were prepared from the corresponding cyclic ketones and subjected to S-alkylation by triethyloxonium tetrafluoroborate followed by potassium tert -butoxide treatment to give bicyclic epoxides with new five-membered carbocycles. A related cyclization to a six-membered ring was also observed.