Universität zu Köln

Ratsch, Friederike, Strache, Joss Pepe, Schlundt, Waldemar, Neudoerfl, Joerg-Martin, Adler, Andreas, Aziz, Sarwar, Goldfuss, Bernd and Schmalz, Hans-Guenther ORCID: 0000-0003-0489-1827 (2021). Enantioselective Cleavage of Cyclobutanols Through Ir-Catalyzed C-C Bond Activation: Mechanistic and Synthetic Aspects. Chem.-Eur. J., 27 (14). S. 4640 - 4653. WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 1521-3765

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Abstract

The Ir-catalyzed conversion of prochiral tert-cyclobutanols to beta-methyl-substituted ketones proceeds under comparably mild conditions in toluene (45-110 degrees C) and is particularly suited for the enantioselective desymmetrization of beta-oxy-substituted substrates to give products with a quaternary chirality center with up to 95 % ee using DTBM-SegPhos as a chiral ligand. Deuteration experiments and kinetic isotope effect measurements revealed major mechanistic differences to related Rh-I-catalyzed transformations. Supported by DFT calculations we propose the initial formation of an Ir-III hydride intermediate, which then undergoes a beta-C elimination (C-C bond activation) prior to reductive C-H elimination. The computational model also allows the prediction of the stereochemical outcome. The Ir-catalyzed cyclobutanol cleavage is broadly applicable but fails for substrates bearing strongly coordinating groups. The method is of particular value for the stereo-controlled synthesis of substituted chromanes related to the tocopherols and other natural products.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ratsch, Friederike UNSPECIFIED UNSPECIFIED UNSPECIFIED Strache, Joss Pepe UNSPECIFIED UNSPECIFIED UNSPECIFIED Schlundt, Waldemar UNSPECIFIED UNSPECIFIED UNSPECIFIED Neudoerfl, Joerg-Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Adler, Andreas UNSPECIFIED UNSPECIFIED UNSPECIFIED Aziz, Sarwar UNSPECIFIED UNSPECIFIED UNSPECIFIED Goldfuss, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmalz, Hans-Guenther UNSPECIFIED orcid.org/0000-0003-0489-1827 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-562060
DOI:	10.1002/chem.202004843
Journal or Publication Title:	Chem.-Eur. J.
Volume:	27
Number:	14
Page Range:	S. 4640 - 4653
Date:	2021
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	1521-3765
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CARBON-CARBON BONDS; FACILE OXIDATIVE ADDITION; O-H BONDS; REGIOSPECIFIC SYNTHESIS; HYDROCARBONS; INSERTION; PRODUCTS; ALCOHOLS; ALKENES; WATER Multiple languages Chemistry, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/56206