Short synthesis of 6-oxoprostaglandin E1 and 6-oxoprostaglandin F1α

6-Oxoprostaglandin E₁ methyl ester was synthesized in a single pot from ($\text{R}$)-4-$\text{t}$-butyldimethylsiloxy-2-cyclopentenone by organocopper conjugate addition with an ω side-chain unit, trapping of the resulting enolate with 6-methoxycarbonyl-2-nitrohex-1-ene, and treatment with aqueous titanium(III) trichloride. Hydrolysis of the methyl ester was accomplished by porcine liver esterase. 6-Oxoprostaglandin F_1α, was obtained from 6-nitroprostaglandin E₁ methyl ester in four steps.     

Stereocontrolled synthesis of 7-hydroxy- and 7-acetoxy-PGI2: New stable PGI2 analogues

Stable analogues of PGI₂, 7-hydroxy- and 7-acetoxy-PGI₂, were synthesized from protected PGI₂ methyl ester $\text{1b}$via sulfoxides $\text{6a}$, $\text{6b}$ through stereocontrolled sulfoxide-sulfenate rearrangement.     

Improved synthesis of isocarbacyclin using regioselective alkylation of allylic alcohols

Two efficient syntheses of isocarbacyclin (1) have been realized using highly regioselective direct alkylation of both - and -allylic alcohols (2 and 3)     

A New Desulfurization Method: Application to the Synthesis of 11-Deoxyprostaglandin E2

Alkylation at carbon attached to sulfur of α-phenylthio or α-alkylthioketones, or reductive-alkylation of α-phenylthioketones provided a new regiospecific alkylation method of ketones.^1,2 In these procedures, desulfurization was effected either by reduction with lithium in liquid ammonia^1,2 or by use of Raney Ni-W-2.² Recently, buffered sodium amalgam method has been reported to be effective for desulfurization of β-ketosulfides as well as for desulfonylation of aryl alkyl sulfones.³ We wish to report here that desulfurization of α-phenylthioketones was achieved by treatment of the ketones with zinc and chlorotrimethylsilane. This observation would lead to a facile synthesis of α-substituted ketones.     

Syntheses of (5E)-PGE2 and New 6-Functionalized Derivatives by the Use of Palladium-Catalyzed Decarboxylative Allylic Alkylation

(5 )-Prostaglandin E₂ (7) was synthesized fron ( )-4- -butyldimethylsilyloxy-2-cyclopentenone (1) by 2-alkenyloxycarbonylatlon of the organocopper conjugate-addition adduct (3) followed by intramolecular palladium-catalyzed decarboxylative allylic alkylation. The (5 )-prostaglandin E₂ skeleton was also obtained from the β-keto allylic ester (11) by a similar decarboxylative allylic alkylation. The decarboxylative allylic alkylation of another type of the three-component coupling product (12) gave new 6-methyleneprostaglandin E1 skeleton (15a), which was converted into new 6-methylprosta-glandin I methyl ester (20) 6-methyleneprostaglandin F₁ derivative (16) by two different ways. The stereochemistry of this intramolecular decarboxylative allylic alkylation was discussed in the reaction of 2-[( )- or ( )-2-butenyloxy-carbonyl] cyclopentanone systems.     

Solvent-induced dual chirality switching in the optical resolution of tropic acid via diastereomeric salt formation with (1R,2S)-2-amino-1,2-diphenylethanol

Solvent-induced chirality switching in the optical resolution of racemic tropic acid (TA) with (1R,2S)-2-amino-1,2-diphenylethanol has been demonstrated. Recrystallization of the diastereomeric salt mixture from i-PrOH or EtOH afforded the (S)-TA salt, while the (R)-TA salt was deposited from 1,4-dioxane and water-enriched alcohol solutions. Dual chirality switching was achieved by using two different types of solvents. The X-ray crystal structures of both diastereomeric salts showed that incorporation of the crystallization solvent played a crucial role in stabilizing each diastereomeric salt crystal. The mechanism of chirality switching has been discussed on the basis of the relative stability of the salt, as deduced from their structures.     

Photoxidation of di-t-butyl thioketone

The photo-oxygenation of the title compound leads to the corresponding ketone and sulfine. A mechanism for the reaction is elucidated.