synthesized for the in situ generation of Bis-IBX and catalytic oxidations. The seemingly better solubility of the in situ-generated Bis-IBX and the attenuated reactivity arising from its unique structural features and methoxy substituents allowed the catalytic oxidation of activated alcohols selectively using DIDA/oxone. Chemoselectiveoxidations were demonstrated for substrates containing two different
A Brønsted acid-catalyzed thioacid addition to <i>in situ</i>-generated aldimine for the synthesis of isoindolinones with the <i>N</i>,<i>S</i>-acetal framework
作者:Milon M. Sadhu、Chhavi Khajuria、Vinod K. Singh
DOI:10.1039/d2ob01532c
日期:——
A facile methodology was demonstrated for the synthesis of isoindolinones containing the N,S-acetal framework by employing a Brønsted acid catalyst with a three-component reaction. The reaction proceeded via the addition of thioacid to in situ-generated aldimine followed by lactamization, which involved the formation of one C–S bond and two C–N bonds under easily controlled and ambient reaction conditions
(Nitroaryl)sulfinyl-substituted allenes. Novel and convenient propargyl alcohol synthons in 4 + 2 cycloaddition chemistry
作者:Albert Padwa、William H. Bullock、Bryan H. Norman、John Perumattam
DOI:10.1021/jo00013a033
日期:1991.6
(Nitroaryl)sulfinyl-substituted allenes are conveniently prepared by treating propargyl alcohol or methyl 3-hydroxy-2-butynoate with a (nitroaryl)sulfenyl chloride and triethylamine. These activated allenes undergo 4 + 2 cycloaddition across the C1C2-pi-bond. The initially formed allylic sulfoxide readily undergoes a 2,3-sigmatropic rearrangement to produce a stable sulfenate ester that is easily cleaved with thiophilic reagents. The dienophilic reactivity of the (nitroary)sulfinyl-substituted allene is much greater than the corresponding propargyl alcohol, and the cycloaddition also proceeds with high regioselectivity. The Diels-Alder reaction of [(2-nitrophenyl)-sulfinyl]propadiene with Danishefsky's diene affords meta-substituted benzyl alcohols in high yield. Reaction of the more highly activated methyl 2-[(2-nitrophenyl)sulfinyl]-2,3-butadienoate with Danishefsky's diene followed by treatment of the resulting sulfenate ester with triethyl phosphite produces substituted phthalides in excellent yield. The (2,4-dinitrophenyl)sulfinyl-substituted allene was found to react smoothly with a variety of nitrones to give sulfenate esters of isoxazolidines. These allenyl sulfoxides correspond to formal equivalents of propargyl alcohol, which itself is too unreactive to undergo Diels-Alder chemistry or 1,3-dipolar cycloaddition with nitrones or nitrile oxides.
Facile organocatalytic domino oxidation of diols to lactones by in situ-generated TetMe-IBX
The domino oxidation of diols to lactones is an important transformation, and catalytic protocols that allow this conversion smoothly are scarce. Capitalizing on the established reactivity of tetramethyl-IBX (TetMe-IBX) and its in situ generation in the presence of a co-oxidant, such as oxone, we have shown that a variety of diols can be converted to the corresponding lactones in respectable yields by employing the precursor of TetMe-IBX, namely, tetramethyl-o-iodobenzoic acid (TetMe-IA), as a catalyst in 5 mol % in the presence of 2 equiv of oxone. (c) 2014 Published by Elsevier Ltd.
PADWA, ALBERT;BULLOCK, WILLIAM H.;NORMAN, BRYAN H.;PERUMATTAM, JOHN, J. ORG. CHEM., 56,(1991) N3, C. 4252-4259
作者:PADWA, ALBERT、BULLOCK, WILLIAM H.、NORMAN, BRYAN H.、PERUMATTAM, JOHN