Organocatalytic Asymmetric Synthesis of α-Oxetanyl and α-Azetidinyl Tertiary Alkyl Fluorides and Chlorides
作者:Ransheng Ding、Christian Wolf
DOI:10.1021/acs.orglett.8b00039
日期:2018.2.2
Asymmetric thiourea and squaramide catalysis provides access to synthetically versatile α-oxetanyl and α-azetidinyl alkyl halides exhibiting a tetrasubstituted chiral carbon center with high yields and enantioselectivities. The products are readily transformed with negligible erosion of enantiopurity and excellent diastereoselectivity to a diverse group of multifunctional compounds including fluorooxindoles
Rh(III)-Catalyzed Aryl and Alkenyl C–H Bond Addition to Diverse Nitroalkenes
作者:Tyler J. Potter、David N. Kamber、Brandon Q. Mercado、Jonathan A. Ellman
DOI:10.1021/acscatal.6b03217
日期:2017.1.6
The transition-metal-catalyzed C–H bond addition to nitroalkenes has been developed. Very broad nitroalkene scope was observed for this Rh(III)-catalyzed method, including for aliphatic, aromatic, and β,β-disubstituted derivatives. Additionally, various directing groups and both aromatic and alkenyl C–H bonds were effective in this transformation. Representative nitroalkane products were converted
Synthesis and Functionalization of Azetidine‐Containing Small Macrocyclic Peptides
作者:George J. Saunders、Sam A. Spring、Eleanor Jayawant、Ina Wilkening、Stefan Roesner、Guy J. Clarkson、Ann M. Dixon、Rebecca Notman、Michael Shipman
DOI:10.1002/chem.202400308
日期:2024.5.17
Incorporation of a 3-aminoazetidine (3-AAz) into peptide backbones improves head-to-tail cyclizations compared to unmodified peptides. The azetidine nitrogen can be readily functionalized using substitution or click chemistry. Crystal structure analysis reveals that a 3-AAz modified cyclic tetrapeptide adopts an uncommon all-trans conformation. The 3-AAz provides stability to protease degradation compared
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.