Universität zu Köln

Klare, Helge, Neudoerfl, Jorg M. and Goldfuss, Bernd ORCID: 0000-0002-1814-8818 (2014). New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions. Beilstein J. Org. Chem., 10. S. 224 - 237. FRANKFURT AM MAIN: BEILSTEIN-INSTITUT. ISSN 1860-5397

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Abstract

Ten novel hydrogen-bonding catalysts based on open-chain P-V-amides of BINOL and chinchona alkaloids as well as three catalysts based on rigid cis-P-V-cyclodiphosphazane amides of N-1,N-1-dimethylcyclohexane-1,2-diamine have been developed. Employed in the asymmetric Michael addition of 2-hydroxynaphthoquinone to beta-nitrostyrene, the open-chain 9-epi-aminochinchona-based phosphorus amides show a high catalytic activity with almost quantitative yields of up to 98% and enantiomeric excesses of up to 51%. The cyclodiphosphazane catalysts show the same high activity and give improved enantiomeric excesses of up to 75%, thus representing the first successful application of a cyclodiphosphazane in enantioselective organocatalysis. DFT computations reveal high hydrogen-bonding strengths of cyclodiphosphazane P-V-amides compared to urea-based catalysts. Experimental results and computations on the enantiodetermining step with cis-cyclodiphosphazane 14a suggest a strong bidentate H-bond activation of the nitrostyrene substrate by the catalyst.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Klare, Helge UNSPECIFIED UNSPECIFIED UNSPECIFIED Neudoerfl, Jorg M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Goldfuss, Bernd UNSPECIFIED orcid.org/0000-0002-1814-8818 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-448313
DOI:	10.3762/bjoc.10.18
Journal or Publication Title:	Beilstein J. Org. Chem.
Volume:	10
Page Range:	S. 224 - 237
Date:	2014
Publisher:	BEILSTEIN-INSTITUT
Place of Publication:	FRANKFURT AM MAIN
ISSN:	1860-5397
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Organic Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language DONOR CATALYSTS; BASIS-SETS; DERIVATIVES; NITROALKENES; 2-HYDROXY-1,4-NAPHTHOQUINONES; RECEPTORS; COMPLEXES; ACCURACY; THIOUREA; PROTON Multiple languages Chemistry, Organic Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/44831