Synthesis of Substituted Cyclooctanols by a Samarium(II) Iodide Promoted 8-Endo Radical Cyclization Process
摘要:
Samarium(II) iodide (SmI2) has been employed to promote an efficient 8-endo radical cyclization reaction of a variety of substituted olefinic ketones. Various substituted monocyclic, fused bicyclic, and bridged bicyclic cyclooctanols have been synthesized in fair to excellent yield via this protocol. In addition to delineating the synthetic potential of this reaction, experiments have been conducted to determine the source of reduced, noncyclized byproducts present in this and related SmI2-mediated reactions performed under protic conditions.
Method development for the determination of 1,1-dimethylhydrazine by the high-performance liquid chromatography–mass spectrometry technique
作者:Igors Susinskis、Peteris Mekss、Juris Hmelnickis
DOI:10.1177/1469066718761437
日期:2018.8
Unsymmetrical dimethyl hydrazine is highly toxic, carcinogenic compound, widely used for organic synthesis and drug development. Therefore, due to its high reactivity, direct analysis is problematic. Current study proposes to use derivatization reaction to increase selectivity and sensitivity of high-performance liquid chromatography–mass spectrometry method. Different derivatization agents were tested
Working three shifts: Polyconjugated δ‐diketones are formed stereoselectively in high yields by the gold‐catalyzed rearrangement of 1,6‐diyn‐3‐yl esters. This cascade involves a 1,3‐sigmatropic acyloxy shift, a 5‐exo‐dig cyclization of the resulting allenyne, and an unprecedented 1,5‐sigmatropic shift of an acyl fragment. The usefulness of the products was shown by an efficient acid‐catalyzed transformation
Selective Cleavage of Dimethylhydrazones to the Carbonyl Compounds Using Silica Gel and its Application in the Synthesis of (<i>Z</i>)-9-Tetradecenyl Acetate
作者:R. B. Mitra、G. Bhaskar Reddy
DOI:10.1055/s-1989-27363
日期:——
A new method for the selective hydrolytic cleavage of dimethylhy- drazones consists of treatment of the hydrazones with silica gel (pH 6.80) in wet tetrahydrofuran. Utilizing this method as one of the key steps, (Z)-9-tetradecenyl acetate, the pheromone of Spodoptera frugiperda, was synthesized.
Enantioselective Conia-Ene-Type Cyclizations of Alkynyl Ketones through Cooperative Action of B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <i>N</i>-Alkylamine and a Zn-Based Catalyst
作者:Min Cao、Ahmet Yesilcimen、Masayuki Wasa
DOI:10.1021/jacs.8b13757
日期:2019.3.13
An efficient and highly enantioselective Conia-ene-type process has been developed. Reactions are catalyzed by a combination of B(C6F5)3, an N-alkylamine and a BOX-ZnI2 complex. Specifically, through cooperative action of B(C6F5)3 and amine, ketones with poorly acidic α-C-H bonds can be converted in situ to the corresponding enolates. Subsequent enantioselective cyclization involving a BOX-ZnI2-activated
Tertiary Enamide-Triggered S<sub>E</sub>Ar: Domino Allylation and Enamine-Type Addition
作者:Frédéric Beltran、Laurence Miesch
DOI:10.1021/acs.orglett.8b03987
日期:2019.3.15
ketospiro-enesulfonamides. By treatment with ZrCl4 and allylsilane, an intramolecular electrophilic aromatic substitution and subsequent allylation is observed. By treatment with TiCl4 and allylsilane, a double enamine-type reaction takes place, thus creating simultaneously four contiguous stereogenic centers diastereoselectively.