Oxymercuration Research Articles

Fatty acids, part 38: Neighbouring group participation in the oxymercuration-demercuration reaction. Another route to 1,4- and 1,5-epoxides

Oxymercuration-demercuration of hydroxy alkenes follows an intramolecular pathway to furnish 1,4-epoxides (tetrahydrofurans) when the hydroxyl group is β ( trans only) or γ to a double bond and 1,5-epoxides (tetrahydropyrans) when the hydroxyl group is δ to the double bond. The cis and trans isomers of methyl ricinoleate and methyl 9-hydroxyoctadec-12-enoate, and a series of cis and trans octadecenols (Δ2–Δ6) are used to establish these relationships. 1,4- and 1,5-Epoxides are also formed during the oxymercuration of methyl densipolate and methyl 12,13-dihydroxyoleate and during the hydroxymercuration of methyl octadeca-9,12 and 8,12-dienoates.

The reactivity of alkenes in the oxymercuration reaction

The reactivity of alkenes in the oxymercuration reaction

Fatty acids, part 37: Application of the oxymercuration-demercuration reaction to long-chain unsaturated esters

Methyl oleate is converted in high yield to methyl 9(10)-methoxystearate by reaction with methanol in the presence of mercuric acetate followed by demercuration with sodium borohydride. Similar ethoxy-, hydroxy-, acetoxy-, acetylamino-, and hydroxyethoxystearates result when the nucleophilic solvent is ethanol, water, acetic acid, acetonitrile, and ethane-1,2-diol respectively, sometimes in the presence of DMF or THF as co-solvent. Reactions with hydrogen peroxide or with t-butylhydroperoxide are more complex and give several products. Non-participating substituents (OAc, OMe, CO 2Me) sufficiently close to the reacting double bond influence the proportion of the two possible oxymercuration products. Reaction with several methyl octadecadienoates and with some seed oils is also reported.

Dioscorone. Regioselective Oxxmercuration of 2-Azabicyclo[2. 2]oct-5-ene

Abstract Oxymercuration of 2-azabicylo[2.2.2]oct-5-ane 1 occurs regioselectively to give a50:50 mixture of 5-syn-and 5-anti-isoquinculidinols 2 which can be converted to dioscorone 5.

Intramolecular delivery of a water equivalent in the oxymercuration reaction. Conversion of an allylic alcohol into a cis- vicinal diol

A new directed synthesis of diols from unsturated alcohols involving the oxymercuration-demercuration of hemiacetal intermediates is described.

A new procedure for the identification, analysis, and isolation of long chain alcohols and acids having alkene unsaturation in positions 3,4, or 5

The oxymercuration–demercuration of mono- or poly-enoic long-chain alcohols with Δ3(trans), Δ4(cis or trans), or Δ5(cis or trans) unsaturation to give 2-alkyl cyclic ethers provides a convenient procedure for the identification and/or isolation of these alcohols and of the corresponding acids after reduction.

Branched-chain sugars via the hydroboration—oxidation of unsaturated sugar derivatives

Hydroboration—oxidation of 5- O-benzyl-1,2- O-isopropylidene-3-deoxy-3- C-methylene-α- D-ribofuranose ( 2) afforded 5- O-benzyl-1,2- O-isopropylidene-3- C-methyl-α- D-ribofuranose (3), 5- O-benzyl-1,2- O-isopropylidene-3- C-methyl-α- D-xylofuranose ( 4), and 5- O-benzyl-1,2- O-isopropylidene-3-deoxy-3- C-hydroxymethyl-α- D-ribofuranose ( 5), in the ratio of 5:7:88. The minor ribo-isomer 3 was also synthesized (in 71% yield) by application of a Grignard synthesis to the ketose 1. The oxymercuration—demercuration reaction of the unsaturated sugar derivative 2 failed. The structures of the isomeric branched-chain sugars 3, 4, and 5 were proved by chemical and physical means.

The asymmetric oxymercuration-demercuration of olefins as a route to optically active alcohols

The asymmetric oxymercuration-demercuration of olefins as a route to optically active alcohols

Substituent effects on the oxymercuration–demercuration of long-chain unsaturated esters

In the oxymercuration–demercuration of long-chain unsaturated esters the presence of a substituent (OH, OMe, OAc) affects the proportion of the two isomeric products and, in some cases, furnishes novel products through interaction of the substituent with the intermediate mercury compound.

The oxymercuration of conformationally biassed cyclohex-2-enols

The oxymercuration–reduction of cis-5-t-butylcyclohex-2-enol (I) in 50% aqueous tetrahydrofuran proceeds with high stereoselectivity to give trans-3-hydroxy-cis-5-t-butylcyclohexanol (III). With trans-5-t-butylcyclohex-2-enol (II) the reaction is much less stereoselective and the major product is cis-3-hydroxy-trans-5-t-butylcyclohexanol (IV). Kinetic data for oxymercuration of these and related olefinic substrates have been obtained. The results are considered in terms of the possible directing influence of the hydroxy-group. It is concluded that this influence is predominantly of a polar (inductive) nature, and that a direct stabilising interaction between hydroxy and a cis-vicinal mercury atom is small or non-existent.

Synthesis of olivomycose (2,6-dideoxy-3-C-methyl-L-arabino-hexose)

Oxidation of methyl 4,6–O-benzylidene-2-deoxy-α-L-arabino-hexopyranoside (1) with ruthenium tetroxide gave the 3-ketone 2 in high yield. A Wittig reaction between methylenetriphenylphosphorane and compound 2 gave methyl 4,6-O-benzylidene-2,3-dideoxy-3-C-methylene-α-L-erythro-hexopyranoside (3), which was hydrated by the oxymercuration–demercuration procedure to afford methyl 4,6-O-benzylidene-2-deoxy-3-C-methyl-α-L-arabino-hexopyranoside (4). The reaction of compound 4 with N-bromosuccinimide gave methyl 4-O-benzoyl-6-bromo-2,6-dideoxy-3-C-methyl-α-L-arabino-hexopyranoside (5) in high yield. Treatment of compound 5 with lithium aluminium hydride followed by acid-catalyzed hydrolysis of the resultant product, gave L-olivomycose (6).

Diterpene chemistry. IV. The oxymercuration–demercuration of methyl pimarate and methyl sandaracopimarate

The oxymercuration–demercuration procedure was explored for methyl pimarate and methyl sandaracopimarate. In the first case a dimercurial-monoether was obtained yielding a cyclic ether on demercuration. In the second, a monomercurial was obtained arising from attack on the vinyl group only, and demercuration gave a mixture of alcohols which were oxidized to a methyl ketone, which on hypoiodite degradation yielded a known degradation product of methyl sandaracopimarate. The difference in behavior between the two series is attributed to the proximity of the double bonds in methyl pimarate.

The stereochemistry of the oxymercuration of substituted cyclohex-2-enols

The stereochemistry of the oxymercuration of substituted cyclohex-2-enols

The attempted oxymercuration-demercuration of 2-phenylbornylene

The attempted oxymercuration-demercuration of 2-phenylbornylene

The synthesis of (+)-matatabiether and related methylcyclopentane monoterpenes

The syntheses of(+)-matatabiether (1), neonepetalactone (15) and related alcohols3 and5, and dihydropyran2 are described, 5-Isopropenyl-2-methyl-1-cyclopentene-1-carboxaldehyde (6) was converted by LAH reduction and acetylation to 2-acetoxymethyl-3-isopropenyl-2-methylcyclopentene (8) which was hydroborated to give 3(β-hydroxyisopropyl2-acetoxymethyl-2-methylcyclopentene (9). Hydrolysis of9 and cyclization with acid gave dihydropyran2 and a small amount of matatabiether (1). Oxymercuration demercuration of acetate9 gave a readily separable mixture of 1-acetoxymethyl-4,8-dimethyl-2-oxabicyclo[3.3.0]octane (13) and 8-acetoxymethyl-1,4-dimethyl-2-oxabicyclo[3.2.1]octane (12). Pyrolysis of acetate12 afforded (+)-matatabiether (1), while hydrolysis of12 gave alcohol3.Oxidation and esterification of aldehyde6 gave methyl 5-isopropenyl-2-methyl-1-cyclopentene-1-carboxylate (18). Hydroboration of18 and heating the resulting hydroxyester to 200° gave neonepetalactone15 contaminated by small amounts of dihydronepetalactone20 and an isomeric dihydronepetalactone21. Catalytic hydrogenation of neonepetalactone yields isodihydronepetalactone (22). These conversions establish thecomplete stereochemistry of

Total synthesis of a curvularin isomer

This paper describes a total synthesis of a biogenetically possible, hitherto unknown macrolide 4. Starting with 3,5-dimethoxybenzaldehyde, ketone 5a was generated in five steps. Alkylation of this compound by bromopentene followed by decarboxylation yielded pentenyl ketone 6. Oxymercuration–demercuration followed by dehydration gave cyclic enol ether 8. Oxidation with m-chloroperbenzoic acid led to the macrolide 4.

Oxymercuration of strained olefins. Effect of neighboring groups

Oxymercuration of strained olefins. Effect of neighboring groups

Oxymercuration of Olefins. II. cis- and trans-Oxymercuration of Bicyclo [2.2.2]oct-2-ene

Oxymercuration of Olefins. II. <i>cis-</i> and <i>trans</i>-Oxymercuration of Bicyclo [2.2.2]oct-2-ene

Oxymercuration of D-Glucal and Its 3,4,6-Triacetate

<b>Oxymercuration of D-Glucal and Its 3,4,6-Triacetate</b>

Formula omitted] oxymercuration of norbornene

formula omitted] oxymercuration of norbornene