Ramana, C. V. ; Induvadana, Boddeti ; Srinivas, Burgula ; Yadagiri, Kommagalla ; Deshmukh, Madhusudhan N. ; Gonnade, Rajesh G. (2009) The influence of electronic factors on Pd-mediated cycloisomerization: A systematic investigation of competitive 6-exo-dig versus 7-endo-dig cyclizations of sugar alkynols Tetrahedron, 65 (47). pp. 9819-9832. ISSN 0040-4020
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Official URL: http://www.sciencedirect.com/science/article/pii/S...
Related URL: http://dx.doi.org/10.1016/j.tet.2009.09.071
Abstract
Pd-mediated cycloisomerization of 3-C-propargyl-ribo- and allofuranose derivatives was investigated in detail to understand the influence of electronic factors on the regioselectivity (6-exo- vs 7-endo) of alkynol cycloisomerization leading either to a six- or seven-membered ring. In general, the 6-exo-dig mode of cyclization is facile and is independent of electronic factors. With some of the alkynols, a regioselective (7-endo?) hydration of the alkyne unit was observed and this has been attributed to the participation of C(3)–OH. When the C(3)–OH was protected as its benzyl ether, cycloisomerization of these alkynols occurred exclusively in a 6-exo-dig mode resulting in the corresponding [3.2.1]-bicyclic ketals. Additional control experiments conducted were in support of the participation of C(3)–OH in regioselective alkyne hydration.
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to Elsevier Science. |
| Keywords: | Palladium; Alkynol Cycloisomerization; Bridged Bicyclic Ketal; Sonogashira Coupling; Sugar Alkynol |
| ID Code: | 106137 |
| Deposited On: | 01 Feb 2018 16:55 |
| Last Modified: | 01 Feb 2018 16:55 |
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