Preparation of Benzolactams by Pd(OAc)2-Catalyzed Direct Aromatic Carbonylation
摘要:
We developed a new method for Pd(II)-catalyzed direct aromatic carbonylation in a phosphine-free catalytic system using Pd(OAc)2 and Cu(OAc)2 in an atmosphere of CO gas containing air. The carbonylation proceeded with ortho-palladation, inducing a remarkable site selectivity to afford a variety of five- or six-membered benzolactams from secondary omega-arylalkylamines, such as N-alkylbenzylamines or N-alkylphenethylamines.
A fundamentally newreagent space has been discovered for the Castagnoli-Cushman reaction. Cyclic anhydride has been successfully replaced with CDI-activated monoesters of homophthalic acid allowing direct preparation of tetrahydroisoquinolonic esters. Mechanistic studies suggested a new reaction pathway not involving any previously described alkoxyisocoumarines.
The ortho-nitro effect was discovered in sulfa-Staudinger cycloadditions of ethoxycarbonylsulfene with linear imines. When an ortho-nitro group is present at the C-aryl substituents of linear imines, the sulfa-Staudinger cycloadditions deliver cis-β-sultams in considerable amounts, together with the predominant trans-β-sultams. In other cases, the above sulfa-Staudinger cycloadditions give rise to trans-β-sultams
o-Phenylenediacetic Acid Anhydride in the Castagnoli–Cushman Reaction: Extending the Product Space to ε-Lactams
作者:Mikhail Krasavin、Olga Bakulina、Dmitry Dar’in
DOI:10.1055/s-0036-1588714
日期:2017.6
The diversity of lactam products accessible by the Castagnoli–Cushman reaction (CCR) of imines and dicarboxylic acid anhydrides has been extended to privileged e-lactams. This novel variant of the CCR using o-phenylenediacetic anhydride is often high-yielding and remarkably diastereoselective and allows the use of α-C–H imines.
Extending the Scope of the New Variant of the Castagnoli–Cushman Cyclocondensation onto o-Methyl Benzoic Acids Bearing Various Electron-Withdrawing Groups in the α-Position
involvement of homophthalic acid monoesters in the Castagnoli–Cushman reaction-type cyclocondensation with imines, we tested a number of other o-methyl benzoic acids bearing various electron-withdrawing groups in the α-position. The majority of these substrates delivered the expected tetrahydroisoquinolone adducts on activation with CDI or acetic anhydride. Homophthalic acid mononitriles displayed the
The Use of Aryl-Substituted Homophthalic Anhydrides in the Castagnoli–Cushman Reaction Provides Access to Novel Tetrahydroisoquinolone Carboxylic Acid Bearing an All-Carbon Quaternary Stereogenic Center
Novel aryl-substituted homophthalicacids were cyclodehydrated to the respective homophthalic anhydrides for use in the Castagnoli-Cushman reaction. With a range of imines, this reaction proceeded smoothly and delivered hitherto undescribed 4-aryl-substituted tetrahydroisoquinolonic acids with remarkable diastereoselectivity, good yields and no need for chromatographic purification. These findings