Shoji Eguchi

A new efficient synthesis of imidazolinones and quinazolinone by intramolecular aza-Wittig reaction

Abstract A new synthesis of imidazolinones and quinazolinones by intramolecular aza-Wittig reaction is described. Readily available azido substituted imides 4 , 6 , 10 , and 12 reacted with triphenylphosphine or tributylphosphine to afford the corresponding imidazolinones 1 , 7 and quinazolinones 2 , 12 via the Staudinger reaction, followed by an intramolecular aza-Wittig reaction.

Studies on hetero-cage compounds—VI : Transannular cyclizations in pentacyclo[6.2.1.0.2,70.4,1005,9]undecan-3,6-dione system

Abstract Several 4-oxa- and -aza-bird-cage compounds were prepared by transannular cyclizations of pentacyclo[6.2.1.0. 2,7 0. 4,10 0 5,9 ]undecan-3,6-dione ( 3 ). Diol derivatives of 3 cyclized to afford the corresponding 4-oxa-bird-cage derivatives such as 9 , 16a and 16b . The corresponding 3-keto-6-ol derivatives ( 6 , 10a and 10b ) did not cyclize transannularly, while 3-imino-6-ol, 3-keto-6-amino, and 3- imino-6-amino type derivatives cyclized to afford 3-substituted 4-oxa- and -aza-bidr-cage compounds such as 12 , 14 and 18 . The transannular cyclization reactivity in the 3 system has been compared with that in the bicyclo[3.3.1]nona-3,7-dione system ( 1 ).

Fullerene glycoconjugates: A general synthetic approach via cycloaddition of per-O-acetyl glycosyl azides to [60]fullerene

Abstract A general synthetic way to incorporate oligosaccharides into [60]fullerene via cycloadditon and deacetylation is presented. The cycloaddition reaction in refluxing chlorobenzene gave a mixture of two unseparable stereoisomers of N-β-glycopyranosyl [5,6]-azafulleroids in 13∼28% yields for per-O-acetyl glycosyl azide of d -glucopyranose, d -galactopyranose, lactose, maltose, and maltotriose.

THE FIRST TOTAL SYNTHESIS OF (-)-BENZOMALVIN A AND BENZOMALVIN B VIA THE INTRAMOLECULAR AZA-WITTIG REACTIONS

Abstract The first total synthesis of (−)-benzomalvin A, which possesses 4(3H)-quinazolinone and 1,4-benzodiazepin-5-one moieties, was described. Both of 6- and 7-membered ring skeletons were efficiently constructed by the intramolecular aza-Wittig reactions as the key reactions. The enantiomeric excess of synthetic (−)-benzomalvin A was more than 99.7% based on HPLC analysis using specially modified cellulose as a stationary phase. Furthermore, investigation on a specific conformational dynamic behavior of (−)-benzomalvin A was carried out by NMR studies and X-ray crystallographic analysis, and benzomalvin B was readily synthesized from (−)-benzomalvin A by only two steps.

An efficient functionalization of [60]fullerene. Diels-Alder reaction using 1,3-butadienes substituted with electron-withdrawing and electron-donating (silyloxy) groups

Abstract The Diels-Alder strategy was found suitable for the functionalization of C 60 using 1,3-butadienes substituted with an electron-withdrawing group as well as with an electron-donating group, giving cyclohexene-fused C 60 derivatives having ethoxycarbonyl, acetyl, cyano, phenylsulfonyl and nitro substituents. These cycloadducts were stabilized by conjugation with the substituent and no cycloreversion took place. Though the dienes are electron-deficient in nature, the HOMO (diene) - LUMO (C 60 ) interaction was significant as indicated by PM3 calculations.

Synthesis of stable Δ4-isoxazolines by 1,3-dipolar cycloaddition of 3,4-dihydroisoquinoline N-oxides with alkynes and their rearrangement to isoquinoline-fused pyrroles☆

Abstract Novel stable 4-substituted Δ 4 -isoxazoline derivatives were obtained by cycloaddition reaction of isoquinoline N-oxides with alkynes. The thermal reaction of some 4-isoxazoline derivatives leading to isoquinoline-fused pyrroles was investigated and it was found that the pathway of the rearrangement to pyrroles is consistent with the way involving acylaziridine.

Hetero-diels-alder reaction of fullerene: Synthesis of thiochroman-fused C60 with o-thioquinone methide and oxidation to its S-oxides

Cycloaddition reaction of C60 with o-thioquinone methide afforded a thiochroman-fused C60 derivative, using benzothiet as a precursor. The cycloadduct was further oxidized with mCPBA to the corresponding sulfoxide and sulfone. However, the self-sensitized photooxygenation to the sulfoxide was unsuccessful.

A new route to quinazolinones via intramolecular aza-Wittig reaction

Abstract Treatment of the imide derivatives 1 and 3 readily obtainable from 2-azidobenzoyl chloride and the corresponding amide derivatives with triphenylphosphine or tributylphosphine in xylene at room temperature gave quinazolinones 2 and 4 in excellent yields via the Staudinger reaction, followed by the intramolecular aza-Wittig reaction.

Synthesis of heterocycle-linked [60]fullerene derivatives by heterocyclic o-quinodimethane Diels-Alder reaction and self-sensitized photooxygenation of the cycloadducts

[60]Fullerene underwent [4+2]cycloaddition reaction smoothly with heteroaromatic analogs of o-quinodimethanes including furan, thiophene, oxazole, thiazole, indole and quinoxaline to give the corresponding heterocycle-linked [60]fullerenes. Among them, the furan and oxazole derivatives were prepared with all equipments covered with an aluminum foil, because of lability to oxygen under exposure to room and sun lights. Intended self-sensitized photooxygenation afforded epoxy-γ-lactone from the former and diester from the latter after methanolysis and hydrolysis.

1,3-Dipolar cycloaddition reactions of substituted 3,4-dihydroisoquinoline N-oxides with allenes

Abstract A study of the 1,3-dipolar cycloaddition behavior of a series of substituted 3,4-dihydroisoquinoline N -oxides with electron-deficient allenes has been carried out. The 1,3-dipolar cycloaddition reaction proceeds in high yield with complete regioselectivity to give 5-methylene isoxazolidines. The stability of these 5-methylene isoxazolidines was depending on the structure of nitrones and allenes.