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Photoactivated Tungsten Hexacarbonyl-Catalyzed Conversion of Alkynols to Glycals

Wipf, P and Graham, TH (2003) Photoactivated Tungsten Hexacarbonyl-Catalyzed Conversion of Alkynols to Glycals. Journal of Organic Chemistry, 68 (23). 8798 - 8807. ISSN 0022-3263

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Abstract

The photoactivated W(CO)6/DABCO/THF system has been used for the formal endo-cyclization of alkynes to pyran rings. We found that the regioselectivity of ring closure depends on the relative configuration of the 3,5-dihydroxy-1-alkynes, as well as, more decisively, on the type of O-protective group. Oxygen substitution at the propargylic carbon slows the rate of alkyne insertion and allows for dihydrofuran formation through exo-cyclization. In contrast, the use of bulky silyl ethers or carbon substituents leads to dihydropyrans through endo-cyclization. Substrates bearing leaving groups such as esters, phenols, or thiophenols at the propargylic site eliminate and thus represent a limitation to the cycloisomerization methodology. Propargyl vinyl ethers will rearrange to give dienals instead of glycals. 1,2-Wittig rearrangement products of dihydropyrans are readily prepared and converted to complex bicyclic building blocks for organic synthesis.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Wipf, Ppwipf@pitt.eduPWIPF
Graham, TH
Date: 14 November 2003
Date Type: Publication
Journal or Publication Title: Journal of Organic Chemistry
Volume: 68
Number: 23
Page Range: 8798 - 8807
DOI or Unique Handle: 10.1021/jo034813s
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 0022-3263
MeSH Headings: Alcohols--chemistry; Catalysis; Photochemistry; Tungsten--chemistry
PubMed ID: 14604347
Date Deposited: 30 Jan 2014 18:17
Last Modified: 02 Feb 2019 15:56
URI: http://d-scholarship.pitt.edu/id/eprint/20430

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