An autoxidative approach to 1,2,3,4-tetrahydroisoquinolin-1-one and tetrahydro-β-carbolin-1-one

Treatment of N-benzyl 1,2,3,4-tetrahydroisoquinoline-1-carboxylate with sodium hydride in N,N-dimethylformamide gives the corresponding N-benzyl 1,2,3,4-tetrahydroisoquinolin-1-one in quantitative yield. The N-benzyl 1,2,3,4-tetrahydro-β-carbolin-1-one is prepared in a similar fashion. The N-deprotection occurred concomitantly with the oxidative decarboxylation when the nitrogen was benzyloxycarbonylated. © 2001 Elsevier Science Ltd

Procédé de préparation de composés d'intérêt par cyclisation intramoléculaire et formation d'un pont éther biaryl

Novel method for intermolecular cyclization by formation of a biaryl ether bridge through the reaction as shown above. In formulas (I) and (II) R1 is a nitro radical adjacent to the oxygen bridge, Hal is a fluoride or chlorine atom, R2, R3 and R4 together form a peptidic chain, in the presence of a weak phase in a heterogeneous medium. The invention also concerns compounds of formulas (I) and (II) and the use of compounds of formula (I) to obtain useful compounds

Synthesis of dihydrophenanthridines by a sequence of Ugi-4CR and palladium-catalyzed intramolecular C-H functionalization

Background<p>Small polyfunctionalized heterocyclic compounds play important roles in the drug discovery process and in the isolation and structural identification of biological macromolecules. It is expected that ready access to diverse sets of heterocycles can not only help improving the known biological and pharmacokinetic properties of drugs, but also assist the discovery of molecules that exhibit biological effects beyond those associated with previously known macromolecules. By virtue of their inherent convergence, high productivity, their exploratory and complexity-generating power, multicomponent reactions (MCRs) are undoubtedly well suited for creating molecular diversity. The combination of MCRs with an efficient post-functionalization reaction has proven to be an efficient strategy to increase the skeleton diversity.</p><p>Results</p><p>The Ugi reaction of an o-iodobenzaldehyde (2), an aniline (3), an isocyanide (4), and a carboxylic acid (5) afforded α-acetamido-α-phenylacetamide (6) in good to excellent yields. The palladium-catalyzed intramolecular C-H functionalization of these adducts under ligandless conditions provided the functionalized dihydrophenanthridines (1).</p><p>Conclusion</p><p>Highly functionalized dihydrophenanthridines are synthesized in only two steps from readily accessible starting materials in good to excellent overall yields.</p

Palladium catalyzed reductive deprotection of alloc: Transprotection and peptide bond formation

N-allyloxycarbonyl group could be efficiently removed using sodium borohydride as hydride donor in the presence of catalytic amount of palladium (0). The conditions were applied to chemoselective protecting group transformation (transprotection) and peptide bond formation