eprintid: 20430
rev_number: 22
userid: 1419
dir: disk0/00/02/04/30
datestamp: 2014-01-30 18:17:32
lastmod: 2021-06-12 22:55:53
status_changed: 2014-01-30 18:17:32
type: article
metadata_visibility: show
item_issues_count: 0
eprint_status: archive
creators_name: Wipf, P
creators_name: Graham, TH
creators_email: pwipf@pitt.edu
creators_email: 
creators_id: PWIPF
creators_id: 
title: Photoactivated Tungsten Hexacarbonyl-Catalyzed Conversion of Alkynols to Glycals
ispublished: pub
divisions: sch_as_chemistry
full_text_status: public
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.
date: 2003-11-14
date_type: published
publication: Journal of Organic Chemistry
volume: 68
number: 23
pagerange: 8798 - 8807
refereed: TRUE
issn: 0022-3263
id_number: 10.1021/jo034813s
pmid: 14604347
mesh_headings: Alcohols--chemistry
mesh_headings: Catalysis
mesh_headings: Photochemistry
mesh_headings: Tungsten--chemistry
chemical_names: Alcohols
chemical_names: Tungsten
citation:   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     
document_url: http://d-scholarship-dev.library.pitt.edu/20430/1/licence.txt