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8332459 
Journal Article 
(Nitroaryl)sulfinyl-Substituted Allenes. Novel and Convenient Propargyl Alcohol Synthons in 4 + 2 Cycloaddition Chemistry 
Padwa, A; Bullock, WH; Norman, BH; Perumattam, J 
1991 
Yes 
Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 
56 
13 
4252-4259 
English 
(Nitroaryl)sulfmyl-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 π-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 (nitroaryl)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 Danishesky’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. © 1991, American Chemical Society. All rights reserved.