Universität zu Köln

Falk, Anna, Fiebig, Lukas, Neudoerfl, Joerg-Martin, Adler, Andreas and Schmalz, Hans-Guenther ORCID: 0000-0003-0489-1827 (2011). Rhodium-Catalyzed Enantioselective Intramolecular [4+2] Cycloaddition using a Chiral Phosphine-Phosphite Ligand: Importance of Microwave-Assisted Catalyst Conditioning. Adv. Synth. Catal., 353 (18). S. 3357 - 3363. WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 1615-4169

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Abstract

The use of modular a,a,a',a'-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL)- and 1,1'-bi-2-naphthol (BINOL)-derived phosphine-phosphite ligands (L2*) in the asymmetric rhodium-catalyzed intramolecular [4+2]?cycloaddition (neutral DielsAlder reaction) of (E,E)-1,6,8-decatriene derivatives (including a 4-oxa and a 4-aza analogue) was investigated. Initial screening of a small ligand library led to the identification of a most promising, TADDOL-derived ligand bearing a phenyl group adjacent to the phosphite moiety at the arene backbone. In the course of further optimization studies, the formation of a new, more selective catalyst species during the reaction time was observed. By irradiating the pre-catalyst with microwaves prior to substrate addition high enantioselectivities (up to 93% ee) were achieved. The new cyclization protocol was successfully applied to all three substrates investigated to give the bicyclic products in good yield and selectivity. 31P NMR and ESI-MS measurements indicated the formation of a [Rh(L2*)2]+ species as the more selective (pre-) catalyst.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Falk, Anna UNSPECIFIED UNSPECIFIED UNSPECIFIED Fiebig, Lukas UNSPECIFIED UNSPECIFIED UNSPECIFIED Neudoerfl, Joerg-Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Adler, Andreas UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmalz, Hans-Guenther UNSPECIFIED orcid.org/0000-0003-0489-1827 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-484628
DOI:	10.1002/adsc.201100658
Journal or Publication Title:	Adv. Synth. Catal.
Volume:	353
Number:	18
Page Range:	S. 3357 - 3363
Date:	2011
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	1615-4169
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language DIELS-ALDER REACTIONS; ASYMMETRIC HYDROGENATION; MECHANISTIC ASPECTS; GRIGNARD-REAGENTS; CYCLOISOMERIZATION; DIPHOSPHINES; 1,4-ADDITION; COMPLEXES; ALKENES; DIENES Multiple languages Chemistry, Applied; Chemistry, Organic Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/48462