Universität zu Köln

Termath, Andreas Ole, Velder, Janna, Stemmler, Rene T., Netscher, Thomas, Bonrath, Werner and Schmalz, Hans-Guenther ORCID: 0000-0003-0489-1827 (2014). Total Synthesis of (2RS)-alpha-Tocopherol through Ni-Catalyzed 1,4-Addition to a Chromenone Intermediate. Eur. J. Org. Chem., 2014 (16). S. 3337 - 3341. WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 1099-0690

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Abstract

A novel strategy for the total synthesis of a-tocopherol (vitamin E) was elaborated on the basis of the conjugate addition of AlMe3 (as a methyl anion equivalent) to a 2-substituted chromenone. Starting from trimethylhydroquinone and (R,R)-hexahydrofarnesol, the required chromenone substrate was efficiently prepared in a short sequence exploiting a TiCl4-mediated Fries rearrangement and a KOtBu-induced Baker-Venkatamaran rearrangement. The envisioned key step, which sets up the quaternary center at C2, was performed in virtually quantitative yield through Ni-catalyzed conjugate addition of AlMe3. However, this transformation, which likely proceeds through a radical mechanism, could not be rendered stereoselective by means of chiral ligands. Nevertheless, the elaborated synthesis of (2RS,4'R,8'R)-alpha-tocopherol (2-ambo-alpha-tocopherol) is efficient and challenges the future development of suitable protocols for the asymmetric 1,4-addition.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Termath, Andreas Ole UNSPECIFIED UNSPECIFIED UNSPECIFIED Velder, Janna UNSPECIFIED UNSPECIFIED UNSPECIFIED Stemmler, Rene T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Netscher, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Bonrath, Werner UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmalz, Hans-Guenther UNSPECIFIED orcid.org/0000-0003-0489-1827 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-437441
DOI:	10.1002/ejoc.201402240
Journal or Publication Title:	Eur. J. Org. Chem.
Volume:	2014
Number:	16
Page Range:	S. 3337 - 3341
Date:	2014
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	1099-0690
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 ASYMMETRIC CONJUGATE ADDITION; PHOSPHINE-PHOSPHITE-LIGANDS; ALPHA-TOCOPHERYL ACETATE; VITAMIN-E; GRIGNARD-REAGENTS; BIOAVAILABILITY; HYDROGENATION; STEREOISOMERS; TRIMETHYLALUMINUM; REARRANGEMENT Multiple languages Chemistry, Organic Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/43744