AI Article Synopsis
- 1,3,2-diazaphospholene hydrides (DAP-H) allow for effective reduction of polarized double bonds, creating a phosphorus-enolate intermediate for potential reaction processes.
- This study details a novel three-step reaction using DAP-H to transform N-sulfinyl acrylamides into enantio-enriched α-hydroxy amides via conjugate reduction, rearrangement, and bond cleavage.
- The process shows high efficiency and selectivity under mild conditions, simplifying traditional methods by directly using DAP-H for key transformations without additional steps.
Article Abstract
1,3,2-diazaphospholene hydrides (DAP-H) enable smooth conjugate reduction of polarized double bonds. The transiently formed phosphorus-enolate provides a potential platform for reductive α-functionalizations. In this respect, asymmetric C-heteroatom bond forming processes are synthetically appealing but remain elusive. We report a 1,3,2-diazaphospholene-catalyzed three-step cascade reaction of N-sulfinyl acrylamides comprised of conjugate reduction, [2,3]-sigmatropic aza-Mislow-Evans rearrangement and subsequent S-O bond cleavage. The obtained enantio-enriched α-hydroxy amides are formed in good yields and excellent enantiospecificity. The stereo-defined P-bound N,O-ketene aminal ensures an excellent transfer of chirality from the sulfur stereocenter to α-carbon. The transformation operates under mild conditions at ambient temperature. Moreover, DAP-H is a competent reductant for the cleavage of formed sulfenate ester, eliminating the extra step in traditional Mislow-Evans processes.
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| http://dx.doi.org/10.1002/anie.202301076 | DOI Listing |
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Reductive Asymmetric Aza-Mislow-Evans Rearrangement by 1,3,2-Diazaphospholene Catalysis.
Angew Chem Int Ed Engl
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Article Synopsis
- 1,3,2-diazaphospholene hydrides (DAP-H) allow for effective reduction of polarized double bonds, creating a phosphorus-enolate intermediate for potential reaction processes.
- This study details a novel three-step reaction using DAP-H to transform N-sulfinyl acrylamides into enantio-enriched α-hydroxy amides via conjugate reduction, rearrangement, and bond cleavage.
- The process shows high efficiency and selectivity under mild conditions, simplifying traditional methods by directly using DAP-H for key transformations without additional steps.
Diastereoselective Aza-Mislow-Evans Rearrangement of N-Acyl tert-Butanesulfinamides into α-Sulfenyloxy Carboxamides.
Angew Chem Int Ed Engl
November 2018
School of Chemical Science and Technology, Yunnan University, No. 2 North Cuihu Road, Kunming, 650091, China.
A diastereoselective [2,3] rearrangement of O-silyl N-sulfinyl N,O-ketene acetals derived from chiral N-acyl tert-butanesulfinamides was developed, giving α-sulfenyloxy carboxamides with excellent enantioselectivity. Enolization and subsequent silylation of N-acyl tert-butanesulfinamides initiate this aza variant of the Mislow-Evans rearrangement, in which the chirality at the sulfur atom in the rearrangement precursors is faithfully transferred to the α-carbon stereocenter of the products. The Ellman sulfinamide, often used as a chiral ammonia equivalent, can serve in this rearrangement as a chiral precursor for the asymmetric synthesis of α-oxygen-functionalized carboxamides.
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