The efficient isomerisation of a range of γ‐azido substituted vinyl sulfones is reported. The corresponding vinyl azides are typically obtained with high levels of Z‐stereochemistry. An exception is when R is an α‐methyl substituent is present when the E‐vinyl azide was preferred.
Conjugate addition reactions of a (diethoxyphosphinoyl)difluoromethyl anion equivalent to acyclic and cyclic vinyl sulfones
作者:K. Blades、D. Lapôtre、J.M. Percy
DOI:10.1016/s0040-4039(97)01313-0
日期:1997.8
Cerium-mediated conjugateadditions of (diethoxyphosphinoyl)difluoromethyllithium to cyclic vinylsulfones proceeded smoothly; reduction afforded the products of formal alkylation, attaching the difluoromethylene phosphonate group to a secondary carbon atom. With acyclic vinylsulfones, the addition was considerably less efficient and deprotonation competed with addition. Addition failed completely
Stereoselective preparation of vinyl sulfones by protodesilylation of allyl silanes
作者:Raymond L. Funk、Joy Umstead-Daggett、Kay M. Brummond
DOI:10.1016/s0040-4039(00)60467-7
日期:1993.4
Allyl sulfones can be conjugated to furnish vinyl sulfones via allyl silane intermediates. The stereoselectivity observed in the protodesilylation step provides a new method for stereoselective preparation of (E)-di-and trisubstituted vinyl sulfones.
Provided is a method for characterising a polypeptide or a population of polypeptides, which method comprises the steps of: (a) contacting a sample comprising one or more polypeptides with a lysine reactive agent to cap ε-amino groups; (b) optionally reacting the sample of polypeptides with an amine reactive reagent to block α-amino groups; (c) digesting the sample of polypeptides with a cleavage reagent to produce peptide fragments; (d) optionally deactivating the cleavage reagent; (e) removing those peptides having uncapped or unblocked amino groups; and (f) recovering the N-terminal peptides.
Provided is a method for characterising a polypeptide or a population of polypeptides, which method comprises the steps of:
(a) contacting a sample comprising one or more polypeptides with a lysine reactive agent to cap ε-amino groups;
(b) optionally reacting the sample of polypeptides with an amine reactive reagent to block α-amino groups;
(c) digesting the sample of polypeptides with a sequence specific cleavage reagent to produce peptide fragments;
(d) optionally deactivating the cleavage reagent;
(e) removing those peptides having uncapped or unblocked amino groups; and
(f) recovering the N-terminal peptides.