synthetically useful level of reactivity of cyclic sulfamidates toward acetylides is described. Ring-opening reactions of a structurally diverse set of 1,2- and 1,3-cyclic sulfamidates with a range of lithium acetylides from aliphatic, cyclic, aromatic, heteroaromatic, and functionalized alkynes proceed smoothly in a regioselective manner to give the corresponding N-sulfate intermediates. Hydrolysis of these
Enantiopure 1,4-Benzoxazines via 1,2-Cyclic Sulfamidates. Synthesis of Levofloxacin
作者:John F. Bower、Peter Szeto、Timothy Gallagher
DOI:10.1021/ol0712475
日期:2007.8.1
nucleophilic cleavage with 2-bromophenols (and related anilines and thiophenols), followed by Pd(0)-mediated amination to provide an entry to substituted and enantiomerically pure 1,4-benzoxazines (and quinoxalines and 1,4-benzothiazines). This chemistry provides a short and efficient entry to (3S)-3-methyl-1,4-benzoxazine 19, a late stage intermediate in the synthesis of levofloxacin.
Reactivity of cyclic sulfamidates towards phosphonate-stabilised enolates: synthesis and applications of α-phosphono lactams
作者:John F. Bower、Andrew J. Williams、Hannah L. Woodward、Peter Szeto、Ron M. Lawrence、Timothy Gallagher
DOI:10.1039/b706315f
日期:——
Five and six ring α-phosphono lactams 14â20 are available by reaction of 1,2- and 1,3-cyclic sulfamidates respectively with enolates derived from ethyl dialkylphosphonoacetates 3 and 4. Subsequent WadsworthâEmmons olefination provides the enantiomerically pure exo-alkylidene variants e.g.25, which is efficiently converted to vinyl triflate 29 (>98% ee). Suzuki coupling of 29 to a range of aryl and vinyl boronic acids leads to a structurally diverse range of pyrrolidinones exemplified by 30 and 34. The degree of epimerisation at the base-sensitive C(5) stereocentre during the Suzuki coupling of 29 is shown to be dependent on both the nature of the aryl boronic acid and the reaction conditions used.
Cyclic Sulfamidates as Vehicles for the Synthesis of Substituted Lactams
作者:John F. Bower、Jakub Švenda、Andrew J. Williams、Jonathan P. H. Charmant、Ron M. Lawrence、Peter Szeto、Timothy Gallagher
DOI:10.1021/ol048036+
日期:2004.12.1
structurally diverse series of mono- and disubstituted 1,2- and 1,3-cyclic sulfamidates react with stabilized enolates, including malonate and phosphonoacetate variants, to provide, after lactamization, substituted and alpha-functionalized pyrrolidinone and piperidinone derivatives.
Cyclic Sulfamidates as Precursors to Alkylidene Pyrrolidines and Piperidines
作者:John F. Bower、Peter Szeto、Timothy Gallagher
DOI:10.1021/ol7022104
日期:2007.11.1
The reaction of the dienolate of ethyl acetoacetate (and related dienolates) with a range of 1,2- and 1,3-cyclic sulfamidates provides an entry to substituted and enantiopure alkylidenated pyrrolidines and piperidines. These heterocycles function as convenient precursors to heterocyclic beta-amino acid derivatives.