Iridium-catalyzed asymmetric hydrogenation of furan derivatives and thiophene 1,1-dioxides / von Larissa Pauli.

Format:

Book

Author/Creator:

Pauli, Larissa, author.

Language:

English

Subjects (All):

Hydrogenation--Congresses.

Hydrogenation.

Thiophenes.

Physical Description:

1 online resource (179 pages)

Place of Publication:

Gottingen, [Germany] : Cuvillier Verlag, 2014.

Summary:

The main focus of the research presented in this dissertation was to broaden the substrate scope of the iridium-catalyzed asymmetric hydrogenation of heterocyclic compounds. In view of the fact that a widely applicable hydrogenation system for the reduction of structurally diverse furans and benzofurans is to date not available, a thorough investigation of furan, benzofuran and thiophene 1, 1-dioxide derivatives was carried out. Mono- and disubstituted furan derivatives were synthesized and submitted to iridium-catalyzed hydrogenation reactions. While 3-substituted furans were reduced using a catalyst based on a cyclopentane-annulated bicyclic pyridine-phosphine ligand with high enantiomeric excess (95-99% ee) and conversion (83-99%), 2-substituted counterparts proved to be less reactive (80-97% conv., 65-82% ee) with the same catalyst. Asymmetric hydrogenation of 2, 4-disubstituted furans proved to be challenging for several reasons, not least because of the problem of controlling the cis/trans selectivity. Surprisingly, in the iridium-catalyzed hydrogenation of 3-substituted benzofurans only one catalyst, based on the cyclohexane-annulated pyridine-phosphinite ligand, showed high activity and enantioselectivity (75-89% conv., 91-92% ee), whereas the five-membered ring analog suffered from moderate activity and enantioselectivity. In contrast, the 2-alkyl substituted benzofurans gave superior results (99% conv., 97-99% ee). Disubstituted thiophene 1, 1-dioxides were also investigated in the iridium-catalyzed asymmetric hydrogenation. The hydrogenation of 3, 4 disubstituted thiophene 1, 1 dioxides using a catalyst based on a cyclopentane-annulated bicyclic pyridine-phosphine ligand gave inferior results to those obtained with their 2, 5 disubstituted counterparts.

Notes:

Includes bibliographical references.

Description based on online resource; title from PDF title page (ebrary, viewed September 27, 2017).

ISBN:

9783736948518

3736948514