Vanadium oxytrichloride oxidation

Vanadyl salts are salts of tetravalent vanadium, and contain the divalent [VO]- radical. Many vanadium compounds are known which appear to contain a [VO] group, but the vanadium is either trivalent or pentavalent. Throughout this book the term vanadyl is restricted to compounds of tetravalent vanadium, that is, to salts of the oxide V02. Hence, for example, the compound VOCI3, which contains pentavalent vanadium, is called vanadium oxytrichloride, and not by the more usual but less logical name vanadyl chloride. ... 

Chemically pure vanadium pentoxide is alternatively prepared by precipitating insoluble mercurous vanadate, HgV03, from a neutral solution of a vanadate, and distilling off the mercury, or by ignition of vanadium salts of volatile acids, for example, vanadium oxytrichloride, VOCl3. The oxide also results from the oxidation of any of the lower oxides, or by the electrolysis of a solution of sodium vanadate or copper vanadate, using a divided cell the last method yields a product of 98 per cent, purity.2... 

In a related study, the diphenolic substrate 409 was oxidized with a large excess of the iron complex [Fe(DMF)3Cl2][FeCl4] to give the spirodienone 413 in 35% yield (193). The oxidative phenolic coupling of 409 to furnish 413 using vanadium oxytrichloride had been previously reported, but the yield was slightly lower (176). Alkaline hydrolysis of 413 to cleave the A -trifluoroacetamide pro-... 

Vanadium oxytrichloride has usually been prepared by the chlorination of vanadium(III) oxide, either alone or mixed with a reducing agent such as carbon.1 The method of preparation described below avoids the use of free chlorine and the potentially hazardous distillation from sodium, which are the most undesirable features of the classical method further, it requires only a minimum amount of apparatus. 

OXIDATIVE PHENOL COUPLING Thal-lium(lll) trifluoroacetate. Vanadium oxytrichloride. 

VANADIUM BROMIDE see VEKOOO VANADIUM CHLORIDE see VEFOOO VANADIUM(III) CHLORIDE see VEPOOO VANADIUM COMPOUNDS see VCZOOO VANADIUM DUST and FUME (ACGIH) see VDUOOO VANADIUM DUST and FUME (ACGIH) see VDZOOO VANADIUM (OSHA) see VDZOOO VANADIUM OXIDE see VEAOOO VANADIUM(V) OXIDE see VDUOOO VANADIUM OXYTRICHLORIDE see VDPOOO VANADIUM PENTAOXIDE see VDUOOO VANADIUMPENTOXID (GERMAN) see VDUOOO VANADIUM PENTOXIDE (dust) see VDUOOO VANADIUM PENTOXIDE (fume) see VDZOOO... 

Phenolic oxidative coupling. Oxidation of reliculine (1) with the reagent in the presence of sodium hydrogen carbonate in chloroform gives isoboldinc (2) in 3 % yield and pallidine (3) in I % yield. Oxidation of reticuline with vanadium oxytrichloride (3, 331-332) gives isoboldine (2) in 1 % yidd and pailadine(3) in 0.3% yield. 

The next most prominent transition metal in Ziegler catalysis is vanadium. In typical fashion, a stable high-oxidation state vanadium compound, such as vanadium oxytrichloride, is reacted with a metal alkyl derivative to generate a reduced form of the... 

The existence of homoerythrina alkaloids has been anticipated from biosynthetic considerations. Homoerythrina dienone 77 was synthesized in the following way. Oxidation of the diphenolic isoquinoline 86 with vanadium oxytrichloride in methylene chloride afforded the expected prohomoerythrinadienone 87 (47), which was transformed to the imine 88 in quantitative yield by 1 N sodium hydroxide at 0°C. Sodium borohydride reduction of the iminium chloride of 88 gave 76. Oxidative phenolic coupling of 76 with potassium hexacyanoferrate in methylene chloride afforded homoerythrina dienone 77 in 45% yield and homoery-sodienone 89a in 15% yield (48). Moreover, the lactam dienone 91 was prepared in excellent yield by oxidation of the N-acyltetrahydroquinoline 90 with potassium ferricyanide (49). 

Use of vanadium oxytrichloride for this type of oxidation results in much improved yields4 and provides the key step in a biogenetic-type synthesis of the Amaryllidaceae alkaloid ( )-maritidine (10). The starting material is O-methyl-... 

PHENOLIC OXIDATIVE COUPLING Ferric chloride. Silver carbonate. Vanadium oxytrichloride. Vanadium tetrachloride. 

C. Coupling reaction using vanadium oxytrichloride (VOCI3) as oxidant... 

The use of vanadium(V) salts in oxidative coupling reactions was prompted by the work of Funk et al. who recognized the ability of vanadium oxytrichloride to form phenoxyvanadium complexes with phenols [llO]. As it was shown by Schwartz et al., such complexes can be isolated and used for oxidative couplings [111]. Vanadium oxytrifluoride, a superior reagent [112] was found to be effective not only with free phenols but also with phenol ethers revealing the non-phenolic mechanism of this oxidation [113]. The method was successfully adapted to the oxidative macrocyclisation of a vancomycin subunit [114]. 

Precaution DOT Corrosive incompat. with strong oxidizing agents, air, moisture, light exposure to moisture in air produces vanadium oxytrichloride... 

Vanadium oxytrichloride is a reagent of general utility in the oxidative coupling of phenolic tetrahydrobenzylisoquinolines. Oxidation of reticuline (12) perchlorate with vanadium oxytrichloride provided isoboldine (13) in 53 7o yield. 

The first synthesis of a homoaporphine by dienone-phenol rearrangement of a homoneoproaporphine is that of Marino and Samanen. The phen-ethyltetrahydroisoquinoline trifluoroacetamide 5 was oxidized with vanadium oxytrichloride to supply the dienone 6 This dienone upon acid-catalyzed rearrangement furnished the homoaporphine trifluoroacetamide 7 in high yield. ... 

Write balanced chemical equations for each of the following verbal descriptions (a) Vanadium oxytrichloride (VOCI3) is formed by the reaction of vanadium(lll) chloride with oxygen, (b) Niobium(V) oxide is reduced to the metal with hydrogen gas. (c) Iron(lll) ion in aqueous solution is reduced to iron(ll) ion in the presence of zinc dust, (d) Niobium(V) chloride reacts with water to yield crystals of niobic acid (HNb03). 

Metal [258], metalloid [259], and nonmetal [260] -based oxidants are very efficient but rather toxic agents thus, vanadium oxytrichloride [258f], 2,6-dicarboxypyridinum chlorochromate (DCPCC) [258a], bis(trimethylsilyl) chromate (BTSC) [258e], chromic acid [261], and selenium... 

Kumar, S., Varshney, S.K. Vanadium oxytrichloride, a novel reagent for the oxidative trimerization of o-dialkoxybenzenes to hexaalkoxytriphenylenes. liq. Cryst. 26, 1841-1843... 

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