Mitsutaka Natsume

Palladium-Catalyzed Intramolecular α-Arylation of Aliphatic Ketones

Cyclization reaction of 5 – 10 using 10 mol% of PdCl2(Ph3P)2 in the presence of 3 eq. of Cs2CO3 in hot THF or toluene afforded bridged or spiro compounds 11 – 16 in good to modest yields.

A Novel Phenol-Forming Reaction for Preparation of Benzene, Furan, and Thiophene Analogs of CC-1065/Duocarmycin Pharmacophores

Abstract A palladium-catalyzed intramolecular coupling reaction between methyl ketones and triflates was developed for preparation of phenol derivatives 13, 14 , and 15 from 10, 11 , and 12 in high yields. Potent antitumor substances 35, 36 , and 37 were prepared from 13, 14 , and 15 .

Total synthesis of lyngbyatoxin A (teleocidin A-1) and teleocidin A-2

Abstract An eleven-step synthesis of tumor promoters, lyngbyatoxin A (=teleocidin A-1) (1) and teleocidin A-2 (2) was achieved from 1-tosylpyrrole (4) using a novel reaction forming 7-alkyl-4-aminoindoles (11).

Synthetic studies of marine alkaloids hapalindoles. Part 3 Total synthesis of (±)-hapalindoles H and U

Abstract A total, synthesis of marine indole alkaloids (±) -hapalindoles H (1) and U (2) was achieved from the previously described compound 7 by way of 13, 21, and 26 for U (2), and 33 and 32 for H (1).

A new synthetic method for the framework of aspidosperma alkaloids using singlet oxygen chemistry

Abstract Abstract1-A singlet oxygen adduct of l-benzyloxycarbonyl-l, 2-dihydro-5-(2-methyl-l,3-dioxolan-2-yl)pyridine 21 was treated with indole in the presence of stannous chloride to yield directly the complex compound 22, which will act as a suitable starting material for the synthesis of various kinds of indole alkaloids. Further transformation from 22, including a new device for construction of the aspidosperma framework, was investigated and pentacyclic compounds 25 (Y = H and OH) were synthesized in moderate yields. The structure of 25 (Y = H) = 38 was confirmed by correlation with l-acetyl-20-deethylaspidospennidine 44. Determination of the structure of a by-product 39 was carried out by single crystal X-ray analysis.

Synthesis of a compound having the essential structural unit for the hetisine-type of aconite alkaloids

Abstract A hexacyclic compound 1 , which carries an almost full structure of the hetisine skeleton lacking only the six-membered ring with an exo methylene group, was synthesized by applying an acetal-ene reaction on 5 for the bond formation of C-14 and C-20 as well as stereoselective hydrocyanation reaction on 7 for construction of the azabicyclo ring system.

Total synthesis of an antitumor antibiotic, (±)-duocarmycin SA

Abstract A 12-step total synthesis of (±)-duocarmycin SA ( 1 ) was achieved from a readily available pyrrole 3 by way of 7,10 / 11,14 and 18 , using a SnCl 2 -mediated reaction of a singlet oxygen adduct 6 with 5 , as well as the Heck and Mitsunobu reactions on 9 and 16 as key steps.

A carbon-carbon bond formation using an endoperoxide of N-methoxy-carbonylpyrrole and a convenient synthesis of 4-alkylindoles

Abstract A convenient synthesis of 4-alkylindoles was attained by utilizing the result of a stannous chloride-effected reaction of endoperoxide of N-methoxycarbonylpyrrole with carbon nucleophiles.

Total synthesis of indole alkaloid pendolmycin

Abstract The teleocidin class of an indole alkaloid, pendolmycin (1) was synthesized from 1-(4-methylphenylsulfonyl)pyrrole in thirteen steps by way of the indole derivative (16), the amino- diester compound (6), and the ethyl carboxylate (5).

A stereoselective synthesis of dl-3-epiuleine

A stereoselective synthesis of an indole alkaloid, 3-epiuleine, in racemic form is described. The key step involved is the ethylation of readily accessible compound 5 with Et2CuLi.