The fate of the tert-butylsulfinyl auxiliary after acid-promoted cleavage-a method for recycling t-BuSONH2
Ellman's chiral auxiliary is converted into tert-butylsulfinyl chloride on sulfinamide deprotection with HCl and can be recovered in high yield upon treatment with ammonia. The enantiopure auxiliary can be obtained by trapping the sulfinyl chloride with a chiral alcohol followed by treatment of the resulting sulfinate ester with LiNH2.
Aggarwal, Varinder K.,Barbero, Nekane,McGarrigle, Eoghan M.,Mickle, Greg,Navas, Raquel,Suárez, José Ramón,Unthank, Matthew G.,Yar, Muhammad
supporting information; experimental part
p. 3482 - 3484
(2009/09/28)
Recycling the tert-butanesulfinyl group in the synthesis of amines using tert-butanesulfinamide
A practical process for recycling the tert-butanesulfinyl group upon deprotection of N-tert-butanesulfinyl amines has been achieved. Treatment of N-tert-butanesulfinyl amines with HCl in cyclopentyl methyl ether results in complete conversion to tert-butanesulfinyl chloride and the corresponding amine hydrochloride salt, which is isolated by filtration in analytically pure form and in quantitative yield. Treatment of the resulting sulfinyl chloride solution with aqueous ammonia then provides analytically pure tert-butanesulfinamide in 97% yield. Alternatively, the tert-butanesulfinyl chloride solution can be treated with ethanol and catalytic quinidine as a sulfinyl transfer catalyst to provide a cyclopentyl methyl ether solution of ethyl tert-butanesulfinate with 88% ee. Addition of NaNH2 in ammonia followed by simple trituration of the product with octane provides tert-butanesulfinamide with 99% ee and in 67% overall isolated yield based upon the starting N-tert-butanesulfinyl amine.
Wakayama, Masakazu,Ellman, Jonathan A.
experimental part
p. 2646 - 2650
(2009/08/15)
Aminohydroxylation of olefins with tert-alkyl sulfonamides
Tert-alkyl sulfonamides chloramine salts are used as nitrogen sources in the catalytic aminohydroxylation and/or aziridination of olefins. The tert-alkyl sulfonamides chloramine salts are close to Chloramine T with respect to their reactivity as nitrogen sources with olefins. However, unlike the tosyl sulfonyl amine group of Chloramine T, the resulting t-alkyl sulfonylamino functionalities can be easily converted to an unprotected amine under mild acidic conditions making the method a simple and cost efficient approach for producing unsubstituted hydroxy amine and/or aziridine products.
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(2008/06/13)
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