83167-23-1Relevant articles and documents
Modular Photocatalytic Synthesis of α-Trialkyl-α-Tertiary Amines
Gaunt, Matthew J.,Harris, Georgia R.,Henry Blackwell, J.,Smith, Milo A.
, p. 15946 - 15959 (2021/10/12)
Molecules displaying an α-trialkyl-α-tertiary amine motif provide access to an important and versatile area of biologically relevant chemical space but are challenging to access through existing synthetic methods. Here, we report an operationally straightforward, multicomponent protocol for the synthesis of a range of functionally and structurally diverse α-trialkyl-α-tertiary amines, which makes use of three readily available components: dialkyl ketones, benzylamines, and alkenes. The strategy relies on the of use visible-light-mediated photocatalysis with readily available Ir(III) complexes to bring about single-electron reduction of an all-alkyl ketimine species to an α-amino radical intermediate; the α-amino radical undergoes Giese-type addition with a variety of alkenes to forge the α-trialkyl-α-tertiary amine center. The mechanism of this process is believed to proceed through an overall redox neutral pathway that involves photocatalytic redox-relay of the imine, generated from the starting amine-ketone condensation, through to an imine-derived product. This is possible because the presence of a benzylic amine component in the intermediate scaffold drives a 1,5-hydrogen atom transfer step after the Giese addition to form a stable benzylic α-amino radical, which is able to close the photocatalytic cycle. These studies detail the evolution of the reaction platform, an extensive investigation of the substrate scope, and preliminary investigation of some of the mechanistic features of this distinct photocatalytic process. We believe this transformation will provide convenient access to previously unexplored α-trialkyl-α-tertiary amine scaffolds that should be of considerable interest to practitioners of synthetic and medicinal chemistry in academic and industrial institutions.
Synthesis and Comparison of Some Cardiovascular Properties of the Stereoisomers of Labetalol
Gold, Elijah H.,Chang, Wei,Cohen, Marvin,Baum, Thomas,Ehrreich, Steward,et al.
, p. 1363 - 1370 (2007/10/02)
A useful method for the separation of labetalol into its two racemic diastereomers, as well as a stereoselective synthesis of its four stereoisomers, is described.The absolute stereochemistry of each isomer was determined by analysis of the CD spectra and confirmed by X-ray analysis.The α- and β1-adrenergic blocking properties, as well as the relative antihypertensive activities, have been measured in rats.The R,R isomer, 2a (SCH 19927), possesses virtually all of the β1-blocking activity elicited by labetalol and displays little α-blocking activity.In contrast, the S,R isomer, 3a, has most of the α-blocking activity.Of the four isomers, only 2a has antihypertensive potency comparable to that of labetalol.These findings, coupled with published data showing that labetalol possesses β-adrenergic mediated peripheral vasodilating activity deriving essentially from its R,R isomer, lead to the following conclusion: The antihypertensive activity of labetalol can be ascribed to at least three identified complementary mechanisms, β-adrenergic blockade, β-adrenergic mediated vasodilatation, and α-adrenergic blockade, whereas the antihypertensive activity of 2a derives from the first two mechanisms only.
