72005-23-3Relevant articles and documents
A Versatile Synthesis of Vinyl-Substituted Heterocycles via Regio- And Enantioselective Pd-Catalyzed Tandem Allylic Substitution
Qian, Chao,Tang, Wenjun,Tang, Wenjun
supporting information, p. 4483 - 4488 (2020/06/05)
We herein report a versatile, regio- and enantioselective palladium-catalyzed tandem allylic substitution powered by a chiral bisphosphorus ligand WingPhos with the palladium loading as low as 0.1 mol %, forming a series of chiral vinyl-substituted heterocycles, including tetrahydroquinoxalines, piperazines, dihydro-2H-benzo[b][1,4]-oxazines, and morpholines, in exellent ee's and yields. The protocol features readily available starting materials, mild reaction conditions, and a broad substrate scope. Mechanistic investigation supports a tandem allylic substitution process.
SN2 Displacement on 2-(Alkylthio)ethyl Derivatives
Herati-Sedaghat, M. R.,McManus, Samuel P.,Harris, J. Milton
, p. 2539 - 2543 (2007/10/02)
We have studied the reaction mechanism of various 2-(alkylthio)ethyl and 2-(arylthio)ethyl derivatives with strong nucleophiles in an attempt to overcome powerful neighboring sulfur participation and shift reaction to a direct displacement SN2 mechanism.The 2,4-dinitrophenolate derivative of specifically deuteriated 2-(methylthio)ethanol reacts by an aromatic substitution mechanism (SNAr) when exposed to amines in aprotoc solvents.Use of sulfonate esters avoids competition from the SNAr mechanism.The rate of reaction of these esters in dimethyl sulfoxide (DMSO) or acetonitrile is independent of concentration of added methylamine, thiourea, urea, or iodide, thus indicating continued SN1 reaction with neighboring sulfur participation.Asd would be expected on this basis, but in contrast to previous mechanistic suggestions, the product for reaction with iodide in acetone shows complete scrambling of methylene groups.In contrast, reaction with thiophenolate ions in DMSO proceeds by direct nucleophilic displacement (an SN2 mechanism), as shown by second-order kinetics and unrearranged product.This is the first demonstration of SN2 displacement on a 2-(alkylthio)ethyl or 2-(arylthio)ethyl derivative.