Synthesis of novel boron containing unnatural cyclic amino acids as potential therapeutic agents
摘要:
Two boronated alpha -amino acids, 1-amino-3-boronocyclopentanecarboxylic acid and 1-amino-3-boronocycloheptanecarboxylic acid were prepared. The key step in the syntheses was the 1,4-boration of the alpha,beta -unsaturated cyclic ketones using the bis-pinacolatodiboron ester to generate the boronated ketones which were then converted to the corresponding amino acids. (C) 2001 Elsevier Science Ltd. All rights reserved.
An effective strategy for synthesis of Cu nanoparticles is designed, these nanoparticles have high catalytic activity in conjugate addition of B2(pin)2 and α,β-unsaturatedketones. The reaction of protodeboration can proceed with adding NaOtBu. In this way, a new method to reduce the conjugated alkenes of α,β-unsaturatedketones is developed with organoboranes as intermediates. Cu nanocrystals also
设计了一种有效的合成铜纳米颗粒的策略,这些纳米颗粒在B 2(pin)2和α,β-不饱和酮的共轭添加中具有高催化活性。原脱硼的反应可以通过添加NaO t Bu来进行。以这种方式,开发了一种以有机硼烷为中间体,还原α,β-不饱和酮的共轭烯烃的新方法。Cu纳米晶体在克级反应和循环利用实验中也具有优异的性能。提出了一种可能的机制。
sp<sup>2</sup>−sp<sup>3</sup> Hybridized Mixed Diboron: Synthesis, Characterization, and Copper-Catalyzed β-Boration of α,β-Unsaturated Conjugated Compounds
作者:Ming Gao、Steven B. Thorpe、Webster L. Santos
DOI:10.1021/ol901359n
日期:2009.8.6
A novel sp2−sp3 hybridized mixed diboron and its reactivity on the copper-catalyzed β-boration of α,β-unsaturated conjugated compounds to afford the corresponding β-borated compounds is reported. The presence of sp3-hybridized boron provides a mild β-boration condition in the absence of phosphine and base additives. Finally, our investigations demonstrate that the sp2-hybridized boron of the mixed
Conjugated aldehydes and ketones undergo reaction with Me2PhSiBpin (pin: pinacolato) catalyzed by Au nanoparticles supported on TiO2 forming exclusively the β-borylation products, via the intermediate formation of the labile silaboration adducts. This chemoselectivity pathway is complementary to the so far known analogous reaction catalyzed by other metals, where β-silylation occurs instead. β-Borylation
Catalytic enantioselective boron conjugate addition to cyclic carbonyl compounds: a new approach to cyclic β-hydroxy carbonyls
作者:Xinhui Feng、Jaesook Yun
DOI:10.1039/b914207j
日期:——
The highly enantioselective conjugate boration of six-membered and seven-membered cyclicenones and unsaturated esters was achieved by the use of a copper-(R,S)-Taniaphos complex with up to 99% ee under optimal conditions.
The use of phosphines to assist the organocatalytic β-boration reaction of α,β-unsaturated carbonyl compounds has been demonstrated with a selected number of substrates. The new method eludes the use of Brönsted bases to promote the catalytic active species and PR3 becomes essential to interact with the substrate resulting in the formation of a zwitterionic phosphonium enolate. This species can further deprotonate MeOH when B2pin2 is present forming eventually the ion pair [α-(H),β-(PR3)-ketone]+[B2pin2·MeO]â that is responsible for the catalysis.