Palladium-mediated Coupling Research Articles

Total Synthesis of Coriandrin

Coriandrin, an antiviral agent, has been synthesized in nine steps from diketone 3. The key steps in the synthesis include an efficient aromatization reaction using N-bromosuccinimide and a palladium-mediated coupling of a benzylic bromide with a vinyl stannane

Synthesis of 1,2,4-triazine-(2H,4H)-3,5,-dione anticoccidial agents via palladium-catalyzed cross-coupling reactions

Palladium-mediated coupling of 2-(4-iodoaryl)-1,2,4-triazine-(2H,4H)-3,5-diones with variously substituted vinylstannanes has been examined in efforts to explore the SAR of novel triazine anticoccidials. Conventional procedures were employed for the large-scale preparation of key iodoaryltriazine intermediates while a new method - employing a modified Shapiro reaction - was developed for the synthesis of 1,1-substituted vinylstannanes.

Silyl Ethers of Stannylated Hydroxymethylfurans and Bromopyrimidinones in Palladium-mediated Coupling Reactions.

Silyl Ethers of Stannylated Hydroxymethylfurans and Bromopyrimidinones in Palladium-mediated Coupling Reactions.

Water facilitation of palladium-mediated coupling reactions

Water facilitation of palladium-mediated coupling reactions

Enantio- and diastereoisomers of 2,4-dimethoxy-5-(2,3-dideoxy-5-O-tritylribofuranosyl)pyrimidine. 2',3'-Dideoxy pyrimidine C-nucleosides by palladium-mediated glycal-aglycon coupling

Newly available enantiomeric 2,3-dideoxy glycals, (5S)- and (5R)-4,5-dihydro-5-[(triphenylmethoxy)methyl]furans and 2,4-dimethoxy-5-iodopyrimidine undergo palladium-mediated coupling by two different, complementary procedures to form enantiomeric pairs of (2',3'-dideoxy-2',3'-didehydrofuranosyl)- and (2',4'-dideoxy-3',4'-didehydrofuranosyl)pyrimidine C-nucleosides. Stereoselective reductions of the carbohydrate unsaturations produce all four enantio- and diastereoisomers of 2,4-dimethoxy-5-(2,3-dideoxy-5-O-tritylribofuranosyl)pyrimidine

Preparation of 1-(tri-n-butylstannyl) furanoid glycals and their use in palladium-mediated coupling reactions

1-(Tri-n-butylstannyl)furanoid glycals have been prepared for the first time by lithiation of the corresponding 3-O-unsubstituted glycals followed by reaction with tri-n-butylstannyl chloride. Furanoid glycals bearing an alkoxy (silyloxy) group at C-3 undergo elimination and furan formation. A 3-O-benzyl-1-(tri-n-butylstannyl)furanoid glycal was prepared from the 1-phenylsulfonyl furanoid glycal using tri-n-butylstannylhydride and AIBN. Stannylated furanoid glycals and iodoaglycon derivatives underwent palladium-mediated coupling to yield the corresponding 1-substituted furanoid glycals in good to excellent yields.

8-Ethenyl-1-hydroxy-4-.beta.-D-ribofuranosylbenzo[d]naphtho[1,2-b]pyran-6-one and 8-ethenyl-1-hydroxy-4-(2'-deoxy-.beta.-D-ribofuranosyl)benzo[d]naphtho[1,2-b]pyran-6-one. Synthetic C-glycosides related to the gilvocarcin, ravidomycin, and chrysomycin antibiotics

Syntheses of 8-ethenyl-1-hydrory-4-β-D-ribofuranosylbenzo[d]naphtho[1,2-b]pyran-6-one (1) and 8-ethenyl- 1-hydrory-4-(2'-deoxy-β-ribofuranosyl)benzo[d]naphtho[1,2-b]pyran-6-one (2) have been accomplished. These two compounds are the first synthetic C-glycosides structurally related to the gilvocarcin, ravidomycin, and chrysomycin antibiotic class which possess the aglycon substituents (hydroxyl at C-1 and ethenyl at C-8) considered critical for the photolytic nicking of DNA.Anthracycline C-glycoside 1 was prepared by a route involving Lewis acid-catalyzed C-glycosyl bond formation between the tetracyclic aglycon and 1,2,3,5-tetra-O-acetyl-D-ribose followed by construction of the aglycon 8-ethenyl substituent from the corresponding ethyl group by radical bromination-dehydrobromination.Synthesis of C-glycoside 2 utilized a different, complementary procedure for C-glycosyl bond formation by palladium-mediated coupling of an iodoaglycon derivative with 1,4-anhydro-2-deoxy-3-O-(tert-butyldiphenylsilyl)-D-erythro-pent-1-enitol,a furanoid glycal designed to form only β C-glycosyl bonds in this reaction

Synthesis of Carbocyclic Nucleoside Analogues by Palladium-Mediated Coupling.

Synthesis of Carbocyclic Nucleoside Analogues by Palladium-Mediated Coupling.

Palladium-mediated coupling of a 3-deoxy pyranoid glycal: stereochemistry of C-glycosyl bond formation

Palladium-mediated coupling of a 3-deoxy pyranoid glycal: stereochemistry of C-glycosyl bond formation

Efficient Synthesis of 2′-Deoxy-β-D-furanosyl C-Glycosides. Palladium-Mediated Glycal-Aglycone Coupling and Stereocontrolled β- and α-Face Reductions of 3-Keto-furanosyl Moieties

ABSTRACT Efficient routes for selective syntheses of 2′-deoxy-β-D-furanosyl C-glycosides have been developed and demonstrated by preparation of the isomers 5-[2′-deoxy-β-D-ribo- (=arabino)furanosyl]-1,3-dimethyl-2,4(1H,3H)-pyrimidinedione and 5-[2′-deoxy-β-D-xylo-(=lyxo)furanosyl]-1,3-dimethyl-2,4(1H,3H)-pyrimidinedione. The syntheses involved regio-and stereospecific palladium-mediated coupling of a new glycal, 1,4-anhydro-2-deoxy-3-O-[(1,1-dimethylethyl)diphenylsilyl]-D-erythro-pent-1-enitol with an appropriate aglycone derivative to form a single 2′-deoxy-3′-keto-β-D-furanosyl C-glycoside (as the corresponding silyl enol ether). Following desilylation, the ketone group of the furanosyl ring was reduced stereo-selectively in either of two ways: by delivery of hydride from (a) the most hindered face of the carbonyl carbon using sodium (triacetoxy)borohydride or (b) the least hindered face using potassium tri-(sec-butyl)borohydride.

Palladium-mediated coupling between organic disulfides and nucleic acid constituents

Palladium-mediated coupling between organic disulfides and nucleic acid constituents

Benzo[d]naphtho[1,2-b]pyran-6-one C-glycosides. Aryltri-n-butylstannanes in palladium-mediated coupling with 2,3-dihydropyran and furanoid glycals

Benzo[d]naphtho[1,2-b]pyran-6-one C-glycosides. Aryltri-n-butylstannanes in palladium-mediated coupling with 2,3-dihydropyran and furanoid glycals

Total synthesis of (±)-ageline a, a physiologically active constituent of Agelas sponges

The monocyclic diterpene moiety of ageline A ( 1) was convergently constructed by the palladium-mediated coupling of C 9-terpenic chain as vinyl bromide 10 and C 11-monocyclic segment as alkylzinc compound 16, which was obtained through a stereoselective cyclization and associated transformations. The appendage of 9-methyladenine ring to the diterpene unit led to the total synthesis of (+)-ageline A.

Pyrido[2,3-d]pyrimidine nucleosides. Synthesis via cyclization of C-5-substituted cytidines

A route to pyrido[2,3-d]pyrimidine nucleosides was developed by starting from cytidine. The two key steps in the synthesis were the palladium-mediated coupling of an a,@-unsaturated ester at the C-5 postion of 5(chloromercuri)cytidine followed by ultraviolet light catalyzed ring closure between N-4 and the ester function. In this way cytidine was transformed in three steps to 3-@-~-ribofuranosyl-2,7-dioxopyrido[2,3-d]pyrimidine (4) when the ester was methyl acrylate. The same sequence of steps from 2'-deoxycytidine and methyl methacrylate led to 3-@-~-(2'-deoxyribofuranosyl)-6-methyl-2,7-dioxopyrido[ 2,3-d]pyrimidine (10). The organopalladium intermediate derived from 5-(chloromercuri)cytidine coupled to acrylonitrile to give, after reduction of an intermediate palladium complex by sodium borohydride, (5-(2-~yanwthyl)cytidine (5). Hydrolysis of 5 in 1 M NaOH proceeds rapidly via cyclization at N-4 to give 5-(2-carboxyethyl)cytidine (7).