Preparation of triarylantimony(V) diacetates and palladium-catalyzed cross-coupling and carbonylative cross-coupling of triarylantimony(V) diacetates and dichlorides with organostannanes

Triarylstibines react with iodobenzene diacetate in dichloromethane to afford triarylantimony(V) diacetates. The cross-coupling and carbonylative cross-coupling of triarylantimony(V) diacetates and dichlorides with organostannanes was accomplished in the presence of PdCl₂ (5 mol%) in CH₃CN at room temperature.     

A facile one-pot procedure for the transformation of acetonides into diacetates catalyzed with Bi(OTf)3·xH2O

The transformation of acetonides into the corresponding diacetates is often required in the synthetic chemistry. An efficient procedure for direct conversion of acetonides into diacetates in the presence of Bi(OTf)₃·xH₂O under mild conditions has been developed. Primary hydroxyl-acetonides could be selectively transformed into diacetates in the presence of anomeric acetonides and the anomeric acetonides could be tunably converted into 2-acetoxyisopropyl or diacetate groups.     

Aryliodine (III) Diacetates as Substrates for Pd-Ag Catalyzed Arylation of Alkenes

An unprecedented application of aryliodine(III) diacetates as substrates in Pd-Ag catalyzed arylation of alkenes is described. The mechanistic studies revealed that the binary Pd-Ag catalysis leads to the decomposition of aryliodine(III) diacetates to oxygen and aryl iodides followed by arylation of alkenes forming Heck-type products. Under optimized conditions both electron-rich and electron-deficient alkenes undergo arylation in high yields. Advantageously, the reaction proceeds smoothly in water as a solvent and neither organic ligands nor inert atmosphere are required.     

Synthesis of (-)-11 Hydroxy-delta8-6a, 10a-trans-tetrahydrocannabinol

When (?)-Δ⁸-6a, 10a-trans-THC (THC = Tetrahydrocannabinol), in the form of its diacetate, was irradiated in the presence of oxygen and a sensitizer, followed by reduction with NaBH₄, three allylic alcohols were formed: (?)-8α-and (?)-8β-hydroxy-Δ^9,11-THC (proportion 3:1) and (?)-9α-hydroxy-Δ^7,8-THC. Acetylation of the epimeric 8-hydroxy-compounds with Ac₂O/pyridine gave the corresponding diacetates. When (?)-Δ⁸-6a, 10a-trans-THC, in the form of its tetrahydropyranyl derivative, was heated with m-chloroperbenzoic acid, the two epimeric 8,9-epoxides were formed in equal amounts. These compounds, on treatment with butyllithium, afforded (?)-8α- and (?)-8β-hydroxy-Δ^9,11- 6a, 10a-trans-THC-tetrahydropyranylether. After removing the protecting group and treatment with Ac₂O/pyridine the same diacetates, as formed by photooxygenation of (?)-Δ⁸-THC-acetate, were obtained as a 1:1-mixture. On heating these epimeric diacetates to 290° they underwent allylic rearrangement to (?)-11-acetoxy-Δ⁸-THC-acetate. From this (?)-11-hydroxy-Δ⁸-6a, 10a-trans-THC was obtained by treatment with LiAlH₄.     

Simple Synthesis of Geminal Diacetates (Acylals) of Aromatic Aldehydes

The geminal diacetates of aromatic aldehydes were prepared from corresponding aldehydes by refluxing with acetic anhydride without any catalysts or even any additional solvent.     

Mild and Efficient Chemoselective Synthesis of Acetals and Geminal Diacetates (Acylals) from Aldehydes using Lanthanum(III) Nitrate Hexahydrate

A mild and efficient chemoselective method has been developed for the preparation of acetals and gem‐diacetates in good to excellent yields through a reaction of aldehydes with ethlyleneglycol or acetic anhydride using catalytic amounts of lanthanum(III) nitrate hexahydrate as a catalyst under solvent‐free conditions.     

A novel route to the F-ring of halichondrin B. Diastereoselection in Pd(0)-mediated meso and C(2) biol desymmetrization

Both sigma and C(2) symmetric diol diacetates were synthesized via two-directional chain elongation. A palladium-mediated, ligand-controlled C(2) diol desymmetrization provided the desired tetrahydrofuran with the correct relative and absolute stereochemistries. Simple functional group manipulation led to the desired F-ring of halichondrin B. Desymmetrization of the meso substrate enantioselectively provided the diastereomer, leading to a refinement of our understanding of the transition state model. [reaction: see text]     

Synthesis,characterization, and crystal structure of 6,7a-dichloro-3a-hydroxyoctahydro-1<Emphasis Type="Italic">H</Emphasis>-indene-2,5-diyl diacetates

The first syntheses and characterizations of 6,7a-dichloro-3a-hydroxyoctahydro-1H-indene-2,5-diyl diacetates were successfully obtained starting from indan-2-ol. Epoxidation of 2 was carried out using mCPBA in methylene chloride followed by acetylation using acetyl chloride to furnish the diacetates. The structures of all synthesized compounds were characterized by spectroscopic methods.     

Chloroferrate(III) Ionic Liquid as Recyclable Catalyst for the Acetylation of Alcohols and Phenols and for 1,1‐Diacylation of Aldehydes

A Lewis acidic ionic liquid, [bmim][FeCl₄], was employed to catalyze acetylation of alcohols and phenols, and the conversion of aldehydes to corresponding 1,1‐diacetates without conventional organic solvents. The catalyst is easily available, water‐tolerant, recoverable and easy to handle.     

Lipase-catalyzed kinetic resolution of threo-configured 1,2-diols: a comparative study of transesterification versus hydrolysis

The kinetic resolution of the α,β-unsaturated vicinal diols 3 has been investigated by irreversible transesterification in organic media and by hydrolysis of the corresponding diacetates 6 (Scheme. 1

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Scheme. 1. Synthesis and kinetic resolution of the diols 3a–e and their corresponding diacetates 6a–e

). The best results were obtained in the hydrolysis of the diacetates with the lipase CAL-B from Candida antarctica as a catalyst.     

CARO'S ACID SUPPORTED ON SILICA GEL. PART VI. A MILD REAGENT FOR REGENERATION OF CARBONYL COMPOUNDS FROM ACETALS,KETALS, AND 1,1-DIACETATES

Efficient conversion of acetals, ketals, and diacetates to carbonyl compounds is described using Caro's acid supported on silica gel. The deacetalization reactions are carried out in acetonitrile at room temperature. Reaction of diacetates is performed in refluxing dichloromethane, and their parent carbonyl compounds are obtained in good-to-excellent yields.     

Heterocycles. 9. 2-Aryl-2H-1,4-tetrahydrooxazines

Reaction of 2-bromo-1-phenylethanones with diethanolamine gave 2-hydroxymorpholines. Acetylation gave mono or diacetates. Acid catalyzed dehydrations gave several types of products whose structures are discussed.     

Synthesis of halogenated monodispersed telechelic oligomers. III. Bistelomerization of allyl acetate with telogens which exhibit α, ω-di(trichloromethyled) end groups

The redox bistelomerization of allyl acetate with telogens which exhibit α, ω-di(trichloromethyled) end groups catalyzed by copper, iron salts, or a ruthenium complex led to monoadducts and telechelic oligomers. These diacetates were quantitatively changed into diols. Such compounds have been characterized by both ¹H- and ¹³C-NMR. A reactivity series has been determined and shows that both end groups must be activated to obtain the expected telechelic products in satisfactory yields.     

Allylic geminal diacetates as a a1,a3 synthon. A convenient synthesis of bicyclo[3.3.1]nonan-9-one derivatives

2-Acetoxy bicyclo[3.3.1]nonan-9-one derivatives could be systhesized from the reaction of allylic 1,1-diol diacetates(1) with pyrrolidine enamine of cyclohexanone under the catalysis of palladium complex in one step.     

Asymmetric allylic alkylation of cycloalkenediol diacetates using a chiral phosphine ligand bearing a carboxyl group

Asymmetric induction in the allylic alkylation of cycloalkenediol diacetates was performed using a chiral alkylphosphine ligand bearing a carboxyl group, 3-(diphenylphosphino)butanoic acid. An increase in enantiomeric excess of the monoalkylated products of cis-cycloalkenediol diacetates was observed through a sequential asymmetric allylic alkylation–kinetic resolution process.     

Novel synthesis of trans-tetrahydro diol diacetates precursors of carcinogenic aza-arene dihydro diols and diol epoxides

Selective dehydrogenation of $\text{trans}$-octahydro diol diacetates of dibenz(a,h)acridine by DDQ provides a convenient synthesis of trans-tetrahydro diol diacetates which are the valuable intermediates for the synthesis of proximate and ultimate carcinogens of dibenz(a,h)acridine.     

Alkene oxidatioh by an iron(II)/persulfate/acetic acid system

Mono- and disubstituted alkenes were converted to trans-vicinal diacetates by heating with an iron(II)/persulfate/acetic acid system. The synthetic utility and limitations were identified. A mechanism for the transformation is proposed which involves an initial addition of sulfate radical anion to the alkena followed by solvolysis, addition, hydrolysis, and aoetylation.     

The isobutane chemical ionization mass spectra of 2-methyl substituted 1,3-cycloalkanediol diacetates and dimethyl ethers

The isobutane chemical ionization mass spectra of 2-methyl-1,3-cyclopentane and 1,3-cyclohexanediol diacetates and dimethyl ethers reveal that the proton bridge in the protonated cis diol derivatives is sensitive to conformational and steric effects. The latter dominate in the case of the methyl ethers on account of the smaller ring created by the proton bridge in the ethers in comparison with the diacetates. Finally, the spectra of the trideuterocetates and trideuteromethyl ethers reveal the occurrence of protolysis in the ionizing plasma.     

Copper- and base-free Sonogashira-type cross-coupling reaction of triarylantimony dicarboxylates with terminal alkynes under an aerobic condition

A simple copper- and base-free palladium-catalyzed Sonogashira-type cross-coupling by the use of triarylantimony dicarboxylates is described. Reaction of triarylantimony diacetates with terminal alkynes in the presence of 1 mol % of PdCl₂(PPh₃)₂ catalyst led to the formation of cross-coupling products in good to excellent yields. The reaction proceeded effectively under an aerobic condition, in that two of the three aryl groups on antimony could be transferred to the coupling products, whereas only one of them was involved in the reaction in an argon atmosphere. The reaction is sensitive to the electronic nature of the diacetates, and those bearing an electron-withdrawing group on the aromatic ring showed higher reactivity than those having an electron-donating group.     

Asymmetric Synthesis of Bicyclic Diol Derivatives through Metal and Enzyme Catalysis: Application to the Formal Synthesis of Sertraline

Enzyme‐ and ruthenium‐catalyzed dynamic kinetic asymmetric transformation (DYKAT) of bicyclic diols to their diacetates was highly enantio‐ and diastereoselective to give the corresponding diacetates in high yield with high enantioselectivity (99.9 % ee). The enantiomerically pure diols are accessible by simple hydrolysis (NaOH, MeOH), but an alternative enzyme‐catalyzed ester cleavage was also used to give the trans‐diol (R,R)‐ 1 b in extremely high diastereomeric purity (trans/cis=99.9:0.1, >99.9 % ee). It was demonstrated that the diols can be selectively oxidized to the ketoalcohols in a ruthenium‐catalyzed Oppenauer‐type reaction. A formal enantioselective synthesis of sertraline from a simple racemic cis/trans diol 1 b was demonstrated.