New Options for the Reactivity of the Burgess Reagent with Epoxides in Both Racemic and Chiral Auxiliary Modes – Structural and Mechanistic Revisions, Computational Studies, and Application to Synthesis

Abstract

The reaction of the chiral auxiliary version of the Burgess reagent with epoxides yields diastereomeric pairs of sulfamidates, which lead to cis and trans amino alcohols in each enantiomeric series. Experimental and spectral details are provided for all new sulfamidates and the products derived from them. Structure revisions have been made for several previously reported products from the reactions of the Burgess reagent with cyclic oxiranes and styrene diols. Considerable revisions are also suggested for the possible mechanisms operating in the reactions of the Burgess reagent with 1,2‐diols and epoxides. Finally, a Density Functional Theory (DFT) study for the interaction of the achiral version of the Burgess reagent with oxiranes is included along with an explanation of the lack of asymmetric induction observed in reactions conducted in a catalytic mode with C2‐symmetric catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A Mild Method for the Synthesis of Carbamate-Protected Guanidines Using the Burgess Reagent

“…On the other hand, the Burgess reagent ( 3 , Figure ) has been used as a powerful dehydrating agent in chemical synthesis for decades. It has also been employed as a convenient source of nitrogen in synthetically useful transformations such as the conversion of alcohols into carbamate derivatives, , 1,2-diols or epoxides into sulfamidates, , aminoalcohols into sulfamides, and sulfoxides into sulfilimines . On the basis of these findings, we hypothesized that it would be possible to prepare carbamate-protected guanidines through rearrangement of intermediate 4 , which can be generated in situ from thiourea and 3 (Scheme ).…”

“…Based on literature precedents, − we propose the following reaction mechanism (Scheme ). The reaction of thiourea 5 with the Burgess reagent 3 affords intermediate 4 .…”

Synthesis of 1,2,3-Triazolium Ionic Liquid-Supported Chiral Imidazolidinones and Their Application in Asymmetric Alkylation Reaction

“…At this stage, we needed to confirm that no epimerization occurred throughout the synthesis route shown in Scheme 1. Therefore, the enantiopurity of the synthesized 1,2,3-triazole-tethered ( S )-4-benzyl-2-imidazolidinone 10a was examined by Mosher’s method [27,28]. For this purpose, 1,2,3-triazole-tethered ( R )-4-benzyl-2-imidazolidinone 10a′ was also prepared by the same synthetic route using Boc- d -Phe-OH instead of Boc- l -Phe-OH (Scheme S1, Supplementary Materials).…”

Design of Thermally Stable Versions of the Burgess Reagent: Stability and Reactivity Study

“…In addition, a serendipidous discovery allowed for a high yield preparation of disulfides from thiols by the action of the Burgess reagent . Details of the synthetic, mechanistic, and computational studies, including modeling by Density Functional Theory and suggestions of possible transition states for the epoxide opening, were published in a recent full paper . Herein we report the synthesis of new versions of the Burgess reagent and their thermal stability profile along with a comparison of their reactivity with the original methyl carbamate compound.…”