211.
Claisen Rearrangement of 2-Propinyl (3-Pyridyl) and Allyl (3-Pyridyl) Ethers
1 Verbindungen vom Typ 1 werden mit Ausnahme von 17 und 25 als Äther benannt. Der systematische Name von 1 ist: 3-(2-Propinyl)oxy-pyridin. 2-Propinyl (3-pyridyl) ether ( 1 ), synthesized from the corresponding 3-pyridinol, was heated in DMF or decane at 208° in a sealed tube. In this way the furopyridines 2 and 3 were formed, and furthermore the pyranopyridine 4 if decane was used as solvent (
Scheme 1). The same reactions took place with (2-methyl-3-pyridyl) 2-propinyl ether ( 14 ). In DMF only 15 , and in decane 16 as well as 15 were formed (
Scheme 3). The rearrangement of the pyridine derivative 17 , which is substituted in both
O-positions to the ether moiety, gave in both DMF and decane the diastereoisomeric tetracyclic compounds 18 and 19 . The same kind of reaction took place with 25 (
Scheme 4). In the thermolysis of the allyl 3-pyridyl ether ( 27 ) cyclization was observed, too. The isolated product has the structure of the dihydrofuropyridine 28 (
Scheme 6). The substituted allyl 3-pyridyl ether 30 reacted in the same way to the dihydrofuropyridine 31 (
Scheme 6).
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