3144-16-9Relevant articles and documents
Selective Late-Stage Sulfonyl Chloride Formation from Sulfonamides Enabled by Pyry-BF4
Gómez-Palomino, Alejandro,Cornella, Josep
supporting information, p. 18235 - 18239 (2019/11/13)
Reported here is a simple and practical functionalization of primary sulfonamides, by means of a pyrylium salt (Pyry-BF4), with nucleophiles. This simple reagent activates the poorly nucleophilic NH2 group in a sulfonamide, enabling the formation of one of the best electrophiles in organic synthesis: a sulfonyl chloride. Because of the variety of primary sulfonamides in pharmaceutical contexts, special attention has been focused on the direct conversion of densely functionalized primary sulfonamides by a late-stage formation of the corresponding sulfonyl chloride. A variety of nucleophiles could be engaged in this transformation, thus permitting the synthesis of complex sulfonamides, sulfonates, sulfides, sulfonyl fluorides, and sulfonic acids. The mild reaction conditions and the high selectivity of Pyry-BF4 towards NH2 groups permit the formation of sulfonyl chlorides in a late-stage fashion, tolerating a preponderance of sensitive functionalities.
Influence of norbornanone substituents on both the Wagner-Meerwein skeletal rearrangements under sulfonation conditions and the diastereoselectivity of the corresponding N,N′-bis-fumaroyl sultams in uncatalyzed Diels-Alder cycloadditions to cyclopenta-1,3-diene
Pia?tek, Anna,Chapuis, Christian
, p. 4247 - 4249 (2013/07/26)
The Wagner-Meerwein domino rearrangement of norbornanone skeletons, under sulfonation conditions, is strongly influenced by the absence of a gem-dimethyl moiety at C(7). As a result, sulfonation at C(10) is less efficient due to a divergent pathway in the intermediate double bond formation and/or isomerization. Furthermore, the absence of such a gem-dimethyl moiety in the corresponding norbornane[10,2]sultam derivatives, sterically influences the orientation of the SO(1) and SO(2) substituents, hence on the π-facial steric shielding of the thermodynamically more stable anti-s-cis N-alkenoyl dienophiles. As a consequence, their diastereoselective [4+2] cycloadditions to cyclopenta-1,3-diene, under nonchelating conditions, are not as efficient due to a less pseudo axial SO(1) and the consequent loss of pseudo C 2-symmetry.
Synthesis of novel chiral Schiff bases and their application in asymmetric transfer hydrogenation of prochiral ketones
Zhou, Zhongqiang,Bian, Yongjun
scheme or table, p. 682 - 687 (2010/11/04)
Novel chiral Schiff bases were synthesized from (+)-camphor, and their application to asymmetric transfer hydrogenation of prochiral ketones is described. The asymmetric transfer hydrogenation reaction could afford excellent conversion rates (up to 97.3%) and up to 27.3% enantiomeric excess.
