Enantioselective alkynylation of benzo[e][1,2,3]-oxathiazine 2,2-dioxides catalysed by (R)-VAPOL-Zn complexes: synthesis of chiral propargylic cyclic sulfamidates

Abstract

(R)-VAPOL-Zn(II) complexes catalysed the enantioselective addition of terminal alkynes to cyclic benzoxathiazine 2,2-dioxides, providing the corresponding chiral propargylic sulfamidates with high yields (up to 93%) and good enantiomeric excesses (up to 87%).

Palladium‐Catalyzed ortho‐Benzoylation of Sulfonamides through C−H Activation: Expedient Synthesis of Cyclic N‐Sulfonyl Ketimines

“…Unfortunately, the Pd-catalyzed CÀ H activation failed with N-methoxy-4-nitrobenzenesulfonamide (2 k) with complete recovery of starting material, probably due to ring deactivation by the nitro group (Table 2, entry 11). Further, by extending the substrate scope of the carbonylation reaction with differently substituted aryl aldehydes gave the corresponding benzoylated derivatives in moderate yields (entries [12][13][14][15][16][17][18][19][20][21]. Interestingly, the halogen-substitutions in the aldehydes as well as sulfonamides were compatible to the optimal reaction conditions and exhibit the desired product in appreciable yield.…”

“…Evidently, the cyclic N-sulfonyl ketimines are privileged structural motifs that show a broad range of biological activities. [12] These have also found applications in organic synthesis, as building blocks, [13] chiral auxiliaries, [14] and directing groups for CÀ H functionalization. [15] Furthermore, cyclic N-sulfonyl ketimines serve as a versatile synthon to access a myriad of S-and N-containing molecules.…”

Iridium(III)‐Catalyzed Selective and Mild C‐H Amidation of Cyclic N‐Sulfonyl Ketimines with Organic Azides

“…[7] N-sulfonyl ketimines are valuable synthons to access a myriad of prevalent nitrogen containing molecules. [8] Although cyclic N-sulfonyl ketimines are commonly used building blocks [9] and chiral auxillaries [10] in many organic transformations, their use as a directing group for CÀH functionalization is still in a primitive stage. In contrast, acyclic N-sulfonyl ketimines are well explored as directing groups.…”

Diarylprolinol as a Ligand for Enantioselective Alkynylation of Cyclic Imines

“…[12] Nevertheless, the alkynylation of benzoxathiazine 2,2dioxides that affords chiral propargylic sulfamidates has been scarcely studied. [13] Sulfamidates are an interesting class of amine derivatives present in some pharmaceuticals and biological active compounds [14] and they also play an important role as building blocks for organic synthesis. [15] For this reason, we focused our efforts in the preparation of chiral propargylic sulfamidates by the direct addition of terminal alkynes to cyclic benzoxathiazine 2,2-dioxides.…”

“…We have recently reported this reaction by using dimethylzinc and (R)-VAPOL as catalyst. [13] However, the reaction did not proceeded with high enantioselectivities (56 to 87% ee) and only a limited number of cyclic imines and aliphatic alkynes were tolerated. In addition, we were not satisfied with the use of the commercially available but expensive (R)-VAPOL.…”