49852-81-5Relevant academic research and scientific papers
PALLADIUM(0) CATALYZED REACTIONS OF 1,4-EPIPEROXIDES
Suzuki, Masaaki,Oda, Yoshihisa,Hamanaka, Nobuyuki,Noyori, Ryoji
, p. 517 - 535 (2007/10/02)
The Pd(PPh3)4 catalyzed reaction of 2,3-saturated and 2,3-unsaturated 1,4-epiperoxides proceeds by courses markedly different from those of the previously reported transition metal catalyses.The Pd(0)-promoted reaction of 2,3-saturated epiperoxides gives the corresponding 4-hydroxy ketones and 1,4-diols as the major products.From 2,3-dedihydroepiperoxides are formed the corresponding 4-hydroxy enones, syn-1,2;3,4-diepoxides, and 1,4-diols.The results are interpreted in terms of competing Pd(0)/Pd(II) exchange mechanisms.Exposure of prostaglandin (PG) H2 methyl esterto Pd(PPh3)4 produces a mixture of methyl esters of PGD2, PGE2, PGF2α, and (5Z,8E,10E,12S)-12-hydroxy-5,8,10-heptadecatrienoic acid.
The Three-Component Coupling Synthesis of Prostaglandins
Suzuki, M.,Yanagisawa, A.,Noyori, R.
, p. 4718 - 4726 (2007/10/02)
A convergent one-pot construction of the prostaglandin (PG) framework has been accomplished by the organocopper-mediated conjugate addition of the S configurated ω side-chain unit to a protected (R)-4-hydroxy-2-cyclopentenone followed by trapping of the enolate intermediate by α side-chain alkyl halides.Transmetalation with use of triphenyltin chloride at the enolate stage serves as key operation for the succesful three-component coupling synthesis.The use of methyl (Z)-7-iodo-5-heptenoate as the α side-chain component allows short synthesis of PGE2 and PGD2.Introduction of a triple bond at the C-5-C-6 positions with methyl 7-iodo-5-heptynoate as the α side-chain synthon has opened a general entry of PGs.The protected 5,6-didehydro-PGE2 derivatives are convertible to a variety of PGs of 1 and 2 series by the controlled hydrogenation of the C-5-C-6 unsaturated bonds and α-selective (100percent) reduction of the C-9 keto function, if necessary.Lithium aluminum hydride reagents modified by (R)- and (S)-2,2'-dihydroxy-1,1'-binaphthyl exhibit a unique kinetic discrimination in reduction of PGE type compounds.A protected 5,6-didehydro-PGF2α has been transformed stereoselectively to PGI2 by using intramolecular alkoxypalladation/depalladation as the key step.
PROSTAGLANDINS: TOTAL SYNTHESIS OF PGD2 "via" 1,3 CYCLOPENTANEDIONE
Cainelli, Gianfranco,Giacomini, Daria,Panunzio, Mauro,Martelli, Giorgio,Spunta, Giuseppe
, p. 1385 - 1392 (2007/10/02)
A practical total synthesis of PGD2 starting from an acyclic precursor is reported.A novel efficient inversion of stereochemistry at C9 tosylate group "via" a SN2 displacement by tetrabutylammonium nitrate is described.
A Short and Efficient Total Synthesis of (+/-) Prostaglandin D2 Methyl Ester involving a New Method for the Cleavage of a Dimethyl-t-butylsilyl Ether
Newton, Roger F.,Reynolds, Derek P.,Webb, Colin F.,Roberts, Stanley M.
, p. 2055 - 2058 (2007/10/02)
Baeyer-Villiger oxidation of the bicycloheptanone (4; R = SiMe2But) afforded a mixture of isomeric lactones (5) and (6), the minor component (6) being conveniently removed by selective hydrolysis.Reduction of the lactone (5) by di-isobutylaluminium hydride gave the corresponding lactol (8).Conversion of (8) into the 9α-silyloxyprostanoid (10) was performed so as to minimise silyl group migration.Oxidation to (10) gave the ketone (12) but the hindered siloxy-group at C-9 was extremely resistant to cleavage by the usual reagents.Satisfactory deprotection of (12) was achieved by treatment with aqueous HF in acetonitrile to give (+/-)-prostaglandin D2 methyl ester (14) and (+/-)-15-epi-prostaglandin D2 methyl ester (15).The high 'silicophilicity' and low acidity of HF make it the reagent of choice for cleavage of silyl ethers under mildly acidic conditions.
