Chiyomi Hashimoto

Photocyclisation of enamides. Part 24. Total synthesis of (±)-isofumigaclavine B and (±)-lysergic acid

Total syntheses of two ergoiine-types of alkaloids, (±)-isofumigaclavine B (14)(for the first time) and methyl (±)-Iysergate (21) and methyl (±)-isolysergate (22), via a route involving reductive photocyclisation of the enamide (2) followed by glycol formation and oxidative cleavage of the dihydrofuran ring, are described.

An improved procedure for the conversion of indolines into indoles

Abstract The addition of a sacrificial enamine (such as indole), or of a vinyl ether (like dihydropyran) to an indoline during dehydrogenation by phenylseleninic anhydride dramatically improves the yield of the corresponding indole. This is due to scavenging of Se 11 phenylselenenating species.

Dehydrogenation with phenylseleninic anhydride in the total synthesis of ergot alkaloids

The standardised procedure for dehydrogenation of indolines into indoles with phenylseleninic anhydride 1 was successfully applied to the final steps in the total synthesis of ergot alkaloids.

Dehydrogenation with benzeneseleninic anhydride in the total synthesis of ergot alkaloids

Investigation of the dehydrogenative conversion of indolines into indoles with benzeneseleninic anhydride (1) resulted in the development of an efficient standardised procedure, which was successfully applied to the final steps in first total synthesis of (±)-lysergol (18), (±)-isolysergol (27), and (±)-elymoclavine (29).

Photocyclisation of enamides. Part 22. Syntheses of the despyrrole analogues of some ergot alkaloids including methyl lysergate and isofumigaclavine A2

A general synthetic route to the benzo[f]quinolines (21)–(27), the despyrrole analogues of lysergic and isolysergic esters and isofumigaclavine A, is described. The route involves the reductive photo-cyclisation of the enamide (2) followed by glycol formation and oxidative ring opening of the dihydrofuran ring.

Photocyclisation of enamides. Part 20. Photocyclisation ofN-naphthylacrylamides and synthesis of the basic indolo[4,3-fg]quinoline nucleus of ergot alkaloids

Photocyclisation of some N-naphthylacrylamides (1)–(6) provided a general synthetic route to benzo [H]-and benzo[f]-quinolines (7)–(12) and two compounds containing the basic indolo[4,3-fg] quinoline nucleus of ergot alkaloids, (17) and (21), were readily prepared.