Synthesis and structure of oxetane containing tripeptide motifs
作者:Nicola H. Powell、Guy J. Clarkson、Rebecca Notman、Piotr Raubo、Nathaniel G. Martin、Michael Shipman
DOI:10.1039/c4cc03507k
日期:——
A new class of peptidomimetic is reported in which one of the amide CO bonds of the peptide backbone is replaced by an oxetane ring. They are synthesised by conjugate addition of various α-amino esters to a 3-(nitromethylene)oxetane, reduction of the nitro group and further coupling with N–Z protected amino acids to grow the peptide chain. Structural insights are provided by X-ray diffraction and molecular dynamics simulations.
Catalytic Enantioselective Addition of Thioacids to Trisubstituted Nitroalkenes
作者:James P. Phelan、Evan J. Patel、Jonathan A. Ellman
DOI:10.1002/anie.201406971
日期:2014.10.13
The first example of a catalyticenantioselectiveaddition to and nitronate protonation of trisubstituted nitroalkenes to produce highly enantioenriched products with a tetrasubstituted carbon is reported. Thioacids added in excellent yields and with high enantioselectivities to both activated and unactivated nitroalkenes. The 1,2‐nitrothioacetate products can be readily converted in two steps to biomedically
Catalytic Enantioselective Addition of Pyrazol-5-ones to Trisubstituted Nitroalkenes with an <i>N</i>
-Sulfinylurea Organocatalyst
作者:James P. Phelan、Jonathan A. Ellman
DOI:10.1002/adsc.201600110
日期:2016.6.2
The first example of enantioselective nitronate protonation following Michaeladdition of a carbon nucleophile to an α,β,β‐trisubstituted nitroalkene is reported. An N‐sulfinylurea catalyst was employed to catalyze the addition of a variety of 3‐substituted pyrazol‐5‐one nucleophiles to trisubstituted nitroalkenes incorporating an oxetane or azetidine ring at the β‐position. The nitroalkane‐pyrazolone
A simple two-step sequence is used to efficiently make novel spirocyclic analogues of the diketopiperazine nucleus. Conjugate addition of chiral -amino esters to nitroalkenes, generated from oxetan-3-one or N-Boc-azetidin-3-one, followed by nitro group reduction provides, after spontaneous cyclization, the spirocycles in good overall yields. These rigid scaffolds can be functionalized by selective N-alkylations as well as by carbonyl reduction to the corresponding piperazines.