No abstract

N-Benzyloxycarbonyl (Cbz)-protected 2-aminoalkanesulfonyl chlorides are useful building blocks for the synthesis of sulfonopeptides, which are receptor ligands and enzyme inhibitors, and are prepared by the coupling reaction of N-protected aminoalkanesulfonyl chlorides with amino acid or peptide esters. Various N-Cbz-protected 2aminoalkanesulfonyl chlorides with functionalized side chains were synthesized through the radical addition of different xanthates to benzyl Nallylcarbamate and subsequent oxidative chlorination with tert-butyl hypochlorite under neutral conditions. A mechanism for the oxidative chlorination is proposed. This is a useful and convenient strategy for the synthesis of N-Cbz-protected 2-aminoalkanesulfonyl chlorides with diverse functionalized side-chains.

The ortho-nitro effect was discovered in sulfa-Staudinger cycloadditions of ethoxycarbonylsulfene with linear imines. When an ortho-nitro group is present at the C-aryl substituents of linear imines, the sulfa-Staudinger cycloadditions deliver cis-β-sultams in considerable amounts, together with the predominant trans-β-sultams. In other cases, the above sulfa-Staudinger cycloadditions give rise to trans-β-sultams exclusively. Further mechanistic rationalization discloses that the ortho-nitro effect is attributed to its strong electron-withdrawing inductive effect. Similarly, the ortho-nitro effect also exists in Staudinger cycloadditions of ethoxycarbonyl ketene with the imines. The current research provides further insights into the diastereoselective control in sulfa-Staudinger and Staudinger cycloadditions.

cyanoacetamides. -A range of N-substituted spiro-cyclohexadienoyl--lactam-3-carbonitriles is prepared by condensation of N-alkylated anilines with cyanoacetic acid followed by oxidative cyclization. -(ABDELLAOUI, H.; XU*, J.; Tetrahedron 70 (2014) 29, 4323-4330, http://dx.