Ketene Acetals. XXXV. Cyclic Ketene Acetals and Orthoesters from 2,2-Dimethoxy-2,3-dihydropyran
β Scribed by McElvain, S. M.; McKay, G. Robert
- Book ID
- 120830860
- Publisher
- American Chemical Society
- Year
- 1955
- Tongue
- English
- Weight
- 850 KB
- Volume
- 77
- Category
- Article
- ISSN
- 0002-7863
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## Abstract For Abstract see ChemInform Abstract in Full Text.
## Abstract 2,2βDialkoxyβ3,4βdihydropyrans (3) can be obtained under mild conditions and in good yields from ketene acetals (1) and Ξ±,Ξ²βunsaturated carbonyl compounds (**2**) in the presence of ZnCl~2~. At low temperatures (< β20Β°C) the reaction between **1** and **2** proceeds as a (2 + 2)βcycload
The 3-or 4-halopyridines and a ketene dialkyl acetal were shown to permit the synthesis of pyrido[b]cyclobutene derivatives. This finding constitutes the first published report of cycloadditions involving an olefin and a 3,4-pyridyne partner. The reaction is totally regioselective and the structure