Synthesis of alkynyl ethers and low-temperature sigmatropic rearrangement of allyl and benzyl alkynyl ethers.
Alpha-alkoxy ketones 3 can be transformed into 1-alkynyl ethers 5 by a two-step procedure involving formation of the enol triflate or phosphate and base-induced elimination. Performing the same reaction sequence with allylic alcohols (R2OH, R2 = allyl) furnishes instead gamma,delta-unsaturated carboxylic acid derivatives 6, derived from [3,3]-sigmatropic rearrangement of the intermediate allyl alkynyl ethers at -78 degrees C and trapping of the subsequently formed ketene with nucleophiles (Nu-H). Benzyl alkynyl ether 5 (R2 = benzyl) rearranges to indanone 7 upon heating to 60 degrees C.
Department of Chemistry and Biochemistry, California State University, Northridge, Northridge, California 91330, USA.
Juan R
JR
Sosa
Armen A
AA
Tudjarian
Thomas G
TG
Minehan
D000480:Alkynes / Q000737:chemistry*; D000577:Amides / Q000737:chemistry; D001554:Benzene / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D004952:Esters / Q000737:chemistry; D004987:Ethers / Q000138:chemical synthesis* / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D008745:Methylation; D015394:Molecular Structure; D013696:Temperature
D000480:Alkynes; D000577:Amides; D002264:Carboxylic Acids; D004952:Esters; D004987:Ethers; D007659:Ketones; D001554:Benzene