Yoshio Ban

New synthesis of heterocycles by use of palladium catalyzed cycli zation of α-haloamide with internal double bond

Abstract α-Haloamide having internal double bond was allowed to react with a catalytic amount of Pd(PPh 3 ) 4 in the presence of base to produce a cyclized product in a fairly good yield possibly through the intermediate of -alkylmetal complex. By use of this method, five and six membered lactams, pyrrolizidine and quinolizidine derivatives were synthesized in fairly good yields.

New synthesis of β-lactams

Abstract α-Methylene-β-lactams 3 were synthesized from the various 2-bromoallylamine derivatives 2 using a catalytic amount of Pd(OAc) 2 or PD(acac) 2 and PPh 3 , under 1–4 atom pressure of CO in good yields. Similarly, α-alkylidene-β-lactams 20 were synthesized from 3-alkyl-2-bromoallylamines 19 , which were easily prepared from the olefins 14 , in the same manner.

A synthetic road to the forest of Strychnos, Aspidosperma, Schizozygane and Eburnamine alkaloids by way of the novel photoisomerization

Abstract The novel photoisomerization of 1-acylindoles accompanied by a conversion of indole to indolenine afforded 3-acylindolenines, a so far unknown reactive species, as a major product. This reaction was thorougly investigated and applied with success to the total synthesis of Strychnos, Aspidosperma, Schizozygane and Eburnamine alkaloids through a versatile intermediate 9-membered ring system, synthesized in a one pot reaction by photolysis and the simultaneous ring enlargement.

Preparation and synthetic use of the zerovalent nickel complex by electrochemical reduction

Abstract The generation of Ni(PPh 3 ) 4 by electrochemical reduction was carried out in a divided cell containing NiCl 2 (PPh 3 ) 4 , PPh 3 and n-Bu 4 NBr in DMF with a lead plate as cathode and a platinum plate as anode under the stream of argon at 60°. Using this Ni(PPh 3 ) 4 , biphenyls and the heterocyclic compounds were synthesized in fairly good yields.

Cyclization of α-haloamide with internal double bond by use of the low-valent metal complex

Abstract The α-haloamide having internal double bond was allowed to react with a catalytic amount of Pd(PPh 3 ) 4 in the presence of proton sponge to produce a cyclized product in a fairly good yield possibly through the intermediation of σ-alkylmetal complex although it was not isolated.

A Convenient Synthesis of Juglone Via Neutral Salcomine Oxidation

Abstract 1,5-Dihydroxynaphthalene and its derivatives can be oxidized by molecular oxygen in the presence of catalytic amounts of salcomine under neutral conditions to afford the corresponding 1,4-naphthoquinones as the major products.

A synthesis of novel nine-membered dienones through a cyclic acetylenic oxy-cope rearrangement: The synthesis of dl-phoracantholide I

Abstract Phoracantholide I, having a ten-membered lactone, was synthesized through a new synthetic method which includes a cyclic acetylenic oxy-Cope rearrangement and ring-expansion by the Baeyer-Villiger oxidation of a nine-membered ketone.

Palladium catalyzed ene-halogenocyclization of α-haloester having internal double bond with the low-valent metal complex

Abstract α-Haloester having internal double bond was reacted with a catalytic amount of Pd(PPh3)4 to afford the cyclized product in good yield and the same product was obtained by treatment of ketene silyl acetal with divalent palladium complex.

Reaction of α-haloester having internal double bond with the low-valent metal complex

Abstract The α-haloester having an internal double bond was allowed to react with a catalytic amount of Pd(PPh 3 ) 4 to afford a cyclized product in a fairly good yield and the same product was obtained by treatment with Pd(OAc) 2 to ketene silyl acetal.

Syntheses of (±)-pyrenophorin and (±)-colletallol

Abstract Pyrenophorin 1 and colletallol 3 were synthesized in their racemic forms from the corresponding hydroxycarboxylic acids 9 and 14 via stereoselective formation of the requisite trans double bonds after macrocyclization.