Oxidation of spiroketones with DDQ - synthesis of tropone derivatives and DDHQ diesters

Oxidation of spiroketones 3a-f with DDQ in dry benzene gave tropone derivatives 4a-f and DDHQ esters 5a-f (cis-cis isomer 6a-f, trans-trans isomer 7a-f). While the aryl substituted spirokeone 17a gave a 2:1 mixture of 19a and the corresponding trans-trans isomer, the aryl substituted spiroketones 17b-d gave exclusively cis?-cis? isomers 19b-d. Heating acid chloride of acid 9c with DDHQ resulted in compounds 4a and 7a, thus confirming the structures assigned. Mechanism of formation of these compounds has been rationalised. A detailed study of 2D 1H-1H COSY, 1H-13C COSY, HMBC and 2D NOESY of compound 7d led to complete assignment of 1H and 13C NMR signals and its solution conformation

Reaction of 4-cyano-1,3-dihydroxy-5,6,7,8-tetrahydroisoquinolines with vilsmeier reagent: structure and mechanism of formation of [2,7]naphthyridines

Reaction of 4-cyano-1,3-dihydroxy-5,6-7,8-tetrahydroisoquinoline 1, with Vilsmeier reagent gave the chloro aldehyde 2, dichloro [2,7]naphthyridine, 5 and monochloro [2,7]naphthyridine 8, identified by spectral data [Mass, 1H & 13C NMR, NOE and HETERO COSY]. Structure 5 has been confirmed by X-ray crystal structure analysis. Reaction of 1a-f, similarly, gave the corresponding compounds 2a-f, 5a-f and 8a-f. The starting tetrahydroisoquinolines, 1a-f were synthesised by the reaction of the corresponding β-keto esters with cyanoacetamide. Reaction of 8 with POCl3 gave in almost quantitative yield, the dichloro compound 5. An acceptable mechanism has been proposed for the formation of the products

Oxidation of spiroketones with DDQ - synthesis of tropone derivatives and DDHQ diesters

Oxidation of spiroketones 3a–f with DDQ in dry benzene gave tropone derivatives 4a–f and DDHQ esters 5a–f (cis -cis isomer 6a–f, (cis -cis isomer 7a–f). While the aryl substituted spirokeone 17a gave a 2:1 mixture of 19a and the corresponding trans -trans isomer, the aryl substituted spiroketones 17b–d gave exclusively trans-trans isomers 19b–d. Heating acid chloride of acid 9c with DDHQ resulted in compounds 4a and 7a, thus confirming the structures assigned. Mechanism of formation of these compounds has been rationalised. A detailed study of 2D 1H-1H COSY, 1H-13C COSY, HMBC and 2D NOESY of compound 7d led to complete assignment of 1H and 13C NMR signals and its solution conformation

Reaction of 4-cyano-1,3-dihydroxy-5,6,7,8-tetrahydroisoquinolines with Vilsmeier Reagent: Structure and Mechanism of Formation of [2,7]naphthyridines

Reaction of 4-cyano-1,3-dihydroxy-5,6-7,8-tetrahydroisoquinoline 1, with Vilsmeier reagent gave the chloro aldehyde 2, dichloro [2,7]naphthyridine, 5 and monochloro [2,7]naphthyridine 8, identified by spectral data [Mass, $^1H$ & $^{13}C$ NMR, NOE and HETERO COSY]. Structure 5 has been confirmed by X-ray crystal structure analysis. Reaction of 1a-f, similarly, gave the corresponding compounds 2a-f, 5a-f and 8a-f. The starting tetrahydroisoquinolines, 1a-f were synthesised by the reaction of the corresponding $\beta$-keto esters with cyanoacetamide. Reaction of 8 with $POCl_3$ gave in almost quantitative yield, the dichloro compound 5. An acceptable mechanism has been proposed for the formation of the products

Reaction of spironaphthalenones with hydroxylamine: Part I. A reinvestigation of the mechanism

Spironaphthalenones 1b-g on reaction with hydroxylamine hydrochloride gave the expected pyrrolotropones 2b-g. Furanotropone 6, postulated as an intermediate in the formation of pyrrolotropones, remained unchanged on reaction with hydroxylamine hydrochloride in ethanol. Reaction of unsymmetrical spironaphthalenones 1h-o with NH2OH.HCl gave the rearranged pyrrolotropones 2h-o

DDQ Oxidation Of Bisnaphthols - Structures Of Novel Products

Oxidation of bisnaphthols (la-c) with DDQ resulted in the formation of lOa-a", lob-b",l4a-c and lea-c in addition to earlier reported products. Structures were assigned OII the basis of detailed spectral analyses ($^1H$, $^{13}C$, $^1H-^1H$ HOMOCOSY and FUCOUP). Structures 10b, 14c and 1Oa were further confirmed by single crystal X-ray analyses. The formation of these compounds has been explained by a suitable mechanism