22381-86-8Relevant academic research and scientific papers
In Situ Methylene Capping: A General Strategy for Efficient Stereoretentive Catalytic Olefin Metathesis. the Concept, Methodological Implications, and Applications to Synthesis of Biologically Active Compounds
Xu, Chaofan,Shen, Xiao,Hoveyda, Amir H.
supporting information, p. 10919 - 10928 (2017/08/15)
In situ methylene capping is introduced as a practical and broadly applicable strategy that can expand the scope of catalyst-controlled stereoselective olefin metathesis considerably. By incorporation of commercially available Z-butene together with robust and readily accessible Ru-based dithiolate catalysts developed in these laboratories, a large variety of transformations can be made to proceed with terminal alkenes, without the need for a priori synthesis of a stereochemically defined disubstituted olefin. Reactions thus proceed with significantly higher efficiency and Z selectivity as compared to when other Ru-, Mo-, or W-based complexes are utilized. Cross-metathesis with olefins that contain a carboxylic acid, an aldehyde, an allylic alcohol, an aryl olefin, an α substituent, or amino acid residues was carried out to generate the desired products in 47-88% yield and 90:10 to >98:2 Z:E selectivity. Transformations were equally efficient and stereoselective with a ～70:30 Z-:E-butene mixture, which is a byproduct of crude oil cracking. The in situ methylene capping strategy was used with the same Ru catechothiolate complex (no catalyst modification necessary) to perform ring-closing metathesis reactions, generating 14- to 21-membered ring macrocyclic alkenes in 40-70% yield and 96:4-98:2 Z:E selectivity; here too, reactions were more efficient and Z-selective than when the other catalyst classes are employed. The utility of the approach is highlighted by applications to efficient and stereoselective syntheses of several biologically active molecules. This includes a platelet aggregate inhibitor and two members of the prostaglandin family of compounds by catalytic cross-metathesis reactions, and a strained 14-membered ring stapled peptide by means of macrocyclic ring-closing metathesis. The approach presented herein is likely to have a notable effect on broadening the scope of olefin metathesis, as the stability of methylidene complexes is a generally debilitating issue with all types of catalyst systems. Illustrative examples of kinetically controlled E-selective cross-metathesis and macrocyclic ring-closing reactions, where E-butene serves as the methylene capping agent, are provided.
Synthesis of allylic and homoallylic alcohols from unsaturated cyclic ethers using a mild and selective C-O reduction approach
MacK, Daniel J.,Guo, Boying,Njardarson, Jon T.
, p. 7844 - 7846 (2012/09/05)
Unsaturated cyclic ethers can be mildly and selectively reduced with catalytic amounts of B(C6F5)3 in the presence of an alkylsilane. The allylic position is preferentially reduced with minimal or no scrambling of olefin geometry. For electronically equivalent substrates, steric factors guide the reducing agent to the least substituted site.
3-AND 4-METHYL-DODECENAL AND THEIR USE IN FRAGRANCE OF FLAVOUR COMPOSITIONS
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Page/Page column 6, (2010/11/25)
3- and 4-Methyl-4-dodecenal, a method of their production and fragrance and flavour compositions comprising at least one of them.
Diastereoselectivity in the [2,3]-sigmatropic rearrangement of substituted allylic N,N-dialkylamidosulfoxylates. X-ray molecular structure of [(1′) S*, (S)S*]-(2′E)-4-[[3′-(4″-bromophenyl)-1′-methyl- 2′-propenyl]sulfinyl]-morpholine
Baudin, Jean-Bernard,Bkouche-Waksman, Itka,Hareau, Georges,Julia, Sylvestre A.,Lorne, Robert,Pascard, Claudine
, p. 6655 - 6672 (2007/10/02)
By the reaction with three N,N-dialkylamidosulfenyl chlorides 2 bearing representative sizes for the R groups on the nitrogen atom, several substituted secondary E or Z allylic alcohols (1a-h) have been converted into the corresponding pairs of diastereoisomeric allylic sulfinamides (3+-3′a-v), whose ratios have been determined by 1H NMR spectroscopy. Five cases of entirely diastereoselective [2,3]-sigmatropic rearrangement have been observed. The stereochemistry of one pure diastereoisomer 3′m has been determined by single crystal X-Ray analysis. When treated with 4-morpholinesulfenyl chloride, cyclohex-2-en-1-ol is stereoselectively converted to one diastereoisomer of the sulfinamide 5b which, by unambiguous procedures, led to the sane p.tolylsulfoxide 5a already obtained by treatment of cyclohex-2-en-1-ol with toluene-p-sulfenyl chloride.
