The conversion of β-amido esters to β-enamino esters is an indispensable step for some synthetic approaches to alkaloids and related medicines. Known methods for such transformation are not only stepwise, but also proceed with low atom-efficiency. Herein, we report a direct and versatile approach that features the Ir-catalyzed chemoselective reduction of β-amido esters with 1,1,3,3-tetramethyldisiloxane
对于某些生物碱和相关药物的合成方法,β-酰胺基酯向β-烯氨基酯的转化是必不可少的步骤。用于这种转化的已知方法不仅是逐步的,而且以低原子效率进行。本文中,我们报道了一种直接且通用的方法,其特征在于用1,1,3,3-四甲基二硅氧烷(TMDS)进行Ir催化的β-酰胺基酯的化学选择性还原。另外,在某些脂环族β-烯胺酯的13 C NMR光谱中观察到缺少某些信号。这揭示了文献中长期存在但被忽略的现象。
Ruthenium-Catalyzed Stereoselective Intramolecular Carbenoid C−H Insertion for <i>β</i>- and <i>γ</i><i>-</i>Lactam Formations by Decomposition of α-Diazoacetamides
作者:Matthew Kwok-Wai Choi、Wing-Yiu Yu、Chi-Ming Che
DOI:10.1021/ol050003m
日期:2005.3.1
alpha-diazoacetamides by intramolecular carbenoid C-H insertion, and beta-lactams were produced in excellent yields and >99% cis-stereoselectivity. The Ru-catalyzed reactions can be performed without the need for slow addition of diazo compounds and inert atmosphere. With alpha-diazoanilides as substrate, the carbenoid insertion was directed selectively to aromatic C-H bond leading to gamma-lactam formation (>95% yield)
Rhodium(III) porphyrin complexes [Rh(Por)Me] are catalytically active towards stereoselectiveintramolecular carbene C–H insertions of α-diazoacetamides to give cis-β-lactams or trans-γ-lactams in yields up to 99% with regioselectivities up to 100% and cis/trans ratios up to 83:17 for β-lactams.
We developed a novel synthetic method of carbamoylacetates from alpha-iodoacetate, carbon monoxide, and amines under photoirradiation conditions in the presence of a Pd catalyst. This reaction likely proceeds via interplay of radical and organopalladium species.