Datta, Apurba ; Ila, Hiriyakkanavar ; Junjappa, Hiriyakkanavar (1987) Polarized ketene dithioacetals 63 : stereoselective synthesis of α-ylidene-γ-butyrolactones Tetrahedron, 43 (22). pp. 5367-5374. ISSN 0040-4020
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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00404...
Related URL: http://dx.doi.org/10.1016/S0040-4020(01)87716-4
Abstract
A facile method for highly stereoselective synthesis of α-arylidene (4a-4d,4f-4h and 4j) and α-ethylidene (4e,4i)-γ-butyrolactones has been developed by acid catalyzed lactonization of the corresponding α-ylidene-γ, δ-unsaturated esters 3a-aj . The required esters 3a-3j were obtained by regioselective reduction of the corresponding α-oxo- α-allyl (or substituted allyl) ketene dithioacetals 1a-1j with sodium borohydride and subsequent boron-trifluoride etherate catalyzed methanolysis of the resultant carbinol acetals 2a-j . Treatment of α-acetylketene dithioacetals 1e and 1i with methylmagnesium iodide afforded the carbinol acetals 5b and 5c respectively which under above sequence of reactions yielded the corresponding α-isopropylidene-γ-butyrolactones 7a and 7b in good yields.
Item Type: | Article |
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Source: | Copyright of this article belongs to Elsevier Science. |
ID Code: | 15399 |
Deposited On: | 13 Nov 2010 08:58 |
Last Modified: | 22 Feb 2011 09:07 |
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