Tungsten-Promoted Intramolecular Annulation of Propargyl Bromides with Ketones and Aldehydes for Synthesis of Fused 2,5-Dihydrofurans
Resource
Journal of Organic Chemistry 61 (10): 3245-3249
Journal
Journal of Organic Chemistry
Journal Volume
61
Journal Issue
10
Pages
3245-3249
Date Issued
1996
Date
1996
Author(s)
Abstract
Metal carbonyl salts CpW(CO)3Na, Re(CO)5Na, and CpFe(CO)2Na were used for intramolecular cyclization of 1-(3-bromo-1-propynyl)-2-(3-oxopropyl)benzene. Among these salts, CpW(CO)3Na was found to be the most effective in yielding a metalated fused �b1-2,5-dihydro-3-furyl complex. To generalize this cyclization, a number of organic substrates containing propargyl bromide and tethered aldehyde or ketone were prepared. Cyclizations of these substrates by CpW(CO)3Na proceeded with moderate yields (50%-65%), producing fused tungsten?�b1-2,5-dihydrofur-3-yl compounds of five-, six-, and seven-membered rings. Demetalations of these organometallic products by (NH4)2Ce(NO3)6 in CH3OH/CH2Cl2 under flowing CO provided fused 3-(methoxycarbonyl)-2,5-dihydrofurans; the yields were 50?60% for most cases. Consecutive oxidations of the representative �b1-2,5-dihydrofur-3-yl complex 15 to its fused �b1-2-furyl and further to �b1-butenolide derivative were accomplished in good yields. Demetalations of these two fused �b1-heterocycles were successful for �b1-butenolide but not for the �b1-2-furyl derivative.
SDGs
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
137.pdf
Size
394.94 KB
Format
Adobe PDF
Checksum
(MD5):6c6ace1f0bc887b29d437d8581996d92