A Simple and Effective Synthesis of Benzolactones and Benzolactams by Noncatalytic­ Benzylic Oxidation of Cyclic Benzylic Ethers and N-Protected Cyclic Benzylic Amines with Sodium Chlorite as an Oxidant

Abstract

Sodium chlorite (NaClO 2 ) was shown to be capable of oxidizing cyclic benzylic ethers and N-protected cyclic benzylic amines in a heterogeneous solvent system of 1,1,1-trichloroethane and water at 55-65°C to give synthetically useful benzolactones and benzolactams, respectively, in high-to-excellent yields.

Rhodium-catalysed tetradehydro-Diels–Alder reactions of enediynes via a rhodium-stabilized cyclic allene

“…Initially, 2a and 2k were converted to biologically important isoindolinone scaffolds 3 and isobenzofuranone 4 : 4 0 respectively, using sodium chlorite as a mild and green oxidizing reagent. 30 Gratifyingly, the N-Ts group could be readily removed from 2a upon sonication in the presence of Mg/MeOH to produce 1-methyl-5-phenylisoindoline 5 in excellent yieldit should be noted, however, that this product is unstable and cannot be puried by chromatography. 31…”

One‐pot Synthesis of 2‐Aminoindole through SET Oxidative Cyclization: Concise Synthesis of Tryptanthrin and Phaitanthrin E

“…Using our one‐pot SET oxidative cyclization strategy, suitably functionalized 2‐aminoindole derivative 10 was readily synthesized from ethyl propiolate, tosylazide and N ‐(2‐bromobenzyl) aniline in 65 % yield (Scheme 6). The key intermediate 10 on SmI 2 ‐mediated detosylation [23] followed by K 2 CO 3 /CuI mediated intramolecular coupling reaction afforded indole‐fused tetracyclic amine 11 in 87 % yield, which on subsequent benzylic oxidation with sodium chlorite [24] afforded a 5 : 4 mixture of phaitanthrin E ( 12 ) and tryptanthrin ( 13 ), respectively, in good yield. Intriguingly, further exposure of phaitanthrin E ( 12 ) to sodium chlorite under oxidation conditions afforded tryptanthrin ( 13 ), indicating that phaitanthrin E could be a biosynthetic precursor of tryptanthrin [25] .…”

Green Oxidation of Isochromans to Isochromanones with Molecular Oxygen Catalyzed by a Tetranuclear Vanadium Cluster

“…The classic benzylic oxidation offers a useful and straightforward approach to synthesize isochromanones using cheap isochromans as the starting materials. [ 3 ] Therefore, the establishment of a green oxidative system for benzylic oxidation with oxygen as the mild oxidant is highly attractive. In the past decades, significant efforts have been directed toward the development of more efficient catalysts and catalytic systems.…”