Mercuric acetate oxidative cyclization

Corynantheidol (255) has been prepared by Hanaoka et al. (155), who started from piperideine derivative 268 and tryptophyl bromide (197). The key cyclization step, resulting in indolo[2,3-a]quinolizine 270 as the major product besides 271, was carried out by mercuric acetate oxidation in the presence of the disodium salt of ethylenediaminetetraacetic acid (EDTA), followed by sodium borohydride reduction. Finally, lithium aluminum hydride reduction of 270 provided ( )-corynantheidol in good yield (155). 

As in the Corey synthesis, an intramolecular Mannich reaction converted 29 to 31. Mercuric acetate oxidation of 31 to the corresponding iminium ion, followed by basification, gave enaminoketone 32. This intermediate does not have the proper stereochemistry for an intramolecular Mannich reaction, but under acidic conditions, epimerization is followed by cyclization to provide 2. The synthesis of porantherine (1) was completed using a Bamford-Stevens reaction to introduce the olefin. ... 

The cyclized analog of meralluride is prepared by a similar synthesis. Thus, condensation of camphoric acid (42) (obtained by oxidation of camphor) with ammonia gives the bicyclic succinimide (44). Reaction with allyl isocyanate followed by ring opening and then reaction with mercuric acetate affords the mercury derivative (45) as the acetate rather than the hydroxide as above. Reaction with sodium chloride converts that acetate to the halide (46). Displacement on mercury with the disodium salt of thioglycollic acid affords the diuretic mercaptomerine (47). ... 

Oxidative cyclization of N- [2-indol-3-yl)ethyl] piperidine (146) with 3 molar equivalents of mercuric acetate and EDTA disodium resulted in ( )-l in 85% yield (106). 

Mercuric acetate and thallic acetate have also been used for the oxidative cydiza-tion of vinylallenes (Eq. 13.24) [29]. Exposure of vinylallene 75 to stoichiometric mercuric acetate in acetic acid led to cydopentenone 76 in 75% yield. With thallium acetate as the oxidant, the yield of 76 was 60%. The presumed mechanism of the oxidative cyclization involves a Nazarov cyclization of acetoxymercury intermediate 77. 

The bishydrazones of the 1,2-diketones from inositols have also been converted into triazoles.222,223 The conversion of arylosazones into the corresponding osotriazoles requires the presence of an oxidant, and it is obvious that simple removal of aniline from the osazone, as suggested by the equation, is not involved. In addition to copper(II) sulfate, the reagent most commonly used, other oxidizing heavy-metal salts, such as ferric sulfate and chloride,224 and mercuric acetate,223 have been used, as well as halogens225 and nitro-sulfonates.226 The osazone acetates are converted into osotriazoles by nitrous acid,227 which decomposes the unacetylated osazones to the aldosuloses228 and the osazone formazans are cyclized with warm... 

Mohrle and Mayer240,241 oxidized the 3-piperidinopropylamine (182) with mercuric acetate-EDTA reagent to obtain the pyrido[l,2-u]pyrimidine (184). Oxidation of the N-monomethyl and N,JV-dimethyl derivatives of 182 resulted in the N-methyl and A,A-dimethypiperidone derivatives of 185.241 If the reactions were carried out without the addition of EDTA, the perhydropyrido[l,2-a]pyrimidine(l83) and its N-methyl derivative also could be isolated from the reaction mixture.241 The pyrido[l,2-a]pyrimidine (184) was also prepared from the piperidone (186).242 The oxidative cyclization was successfully when applied to the piperidinopropionamides (187) to prepare the pyrido[l,2-a]pyrimidines(188) in addition to 2-oxopiperidino-propionamides.243... 

Ankorine (92) has been synthesized from cincholoipon ethyl ester by reaction with 2-benzyloxy-3,4-dimethoxyphenacyl bromide to give (91 X = H2), followed by reduction, oxidation to the lactam by mercuric acetate and EDTA, cyclization,... 

When the unsaturated JV-benzyloxycarbonyl derivative 4 was cyclized with mercuric acetate in tetrahydrofuran (kinetic conditions), the reaction proceeded with total diastereoselectivity, and, after reductive oxidation, the l,3-fra . -derivative 5 was recovered in good yield227. 

Oxidative cyclization. The final step in a synthesis of racemic ajmalicine (2) required oxidative cyclization of (I). This reaction was carried out in 2.5% aqueous acetic acid with an excess of 1 1 mercuric acelale-ethylenediaminetetraacetic acid disodium salt (EDTA, I, 373-374) followed by sodium borohydride reduction of iminium intermediates. 

Mohrle and Gundlach - carried out the oxidative cyclization of the 2-aminobenzylamines 267 with the mercuric acetate-EDTA reagent to obtain the nitrogen bridgehead compounds 270 in 64-80% yields. The oxidation of the tricyclic compounds 270 with manganese dioxide produced the corresponding fused quinazolinones 99. ... 

In support of an ingenious scheme for the biosynthesis of vinca and iboga alkaloids proposed by Wenkert is an interesting synthesis accomplished by Kutney, Brown, and Piers by transannular cyclization of carbomethoxydihydrocleavamine (I), accomplished by oxidation with mercuric acetate in acetic acid at room temperature. Chromatography afforded as the main product the vinca alkaloid vincadifformine. 

Oxidative cyclizations [1, 652, before references] have been realized by Julia, Colomer, and Julia38 by treatment of certain phenyl-substituted olefins with mercuric acetate. 4-Phenyl-1-butene (1) on treatment with mercuric acetate in acetic acid, followed by treatment with perchloric acid, gives a mixture from which the three products formulated were isolated in the low yields indicated (some metallic mercury is deposited). 

Oxidative cyclization Cupric chloride. Manganese dioxide. Mercuric acetate. 

Oxidative cyclization. Treatment of 2 -hydroxychalcones (1) with mercuric acetate in DMSO gives cyclized adducts (2) and aurones (3) the adducts are converted into (3) by further treatment with CaO in DMSO. ... 

The absolute configuration of quebrachamine (XVI) already related to that of aspidospermine (XV see Volume VIII) has been firmly established by oxidative cyclization (mercuric acetate in acetic acid or potassium permanganate in dimethylformamide) of both enantiomers to 1,2-dehydroaspidospermidine (XVII) of the opposite rotational sign, followed by reduction to aspidospermidine (XII 19h, 58). The similarity in the IR- and NMR-spectra as well as the ORD-curves of (-H )-XII and... 

Methylene-y-btttyrolactone (3). An efficient route to this lactone (also known as a -angelicalactone) involves oxidation of 4-pentyne-l-ol (1, Chem. Samples) to 4-pentynoic acid (2) followed by cyclization with mercuric acetate. ... 

Yet another efficient synthesis of evodiamine and rutaecarpine has been reported. This latest one involves the oxidative cyclization of the tetracyclic amide (29) by means of mercuric acetate, which gave ( )-evodiamine (30) in 92% yield (Scheme 5). Oxidation of evodiamine with active manganese dioxide then completed the synthesis of rutaecarpine (26). 

A-Nor-B-homo steroids with different substitution patterns than those described above may be prepared by acid catalyzed cyclization of 3)3-hydroxy-5(10)-seco-cholest-tra/w-l(l0)-en-5-one acetate (134a) formed in 30-40% yield by mercuric oxide-iodine sensitized irradiation of cholestane-3j3,5a-diol... 

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