Synthesis of seven-membered ring glycals via endo-selective alkynol cycloisomerization.
[reaction: see text] Alkynyldiols 1 undergo cycloisomerization to the corresponding seven-membered cyclic enol ethers 2 under tungsten carbonyl catalysis. This novel transformation proceeds with good yields and virtually complete regioselectivity for all diastereomers of 1, favoring the product 2 resulting from endo-mode cyclization. The unexpected regioselectivity may be dependent on the presence of the dioxolane structure tethering the terminal alkyne and diol functional groups.
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
Eva
E
Alcázar
Joseph M
JM
Pletcher
Frank E
FE
McDonald
D000438:Alcohols / Q000737:chemistry*; D003500:Cyclization; D007536:Isomerism
D000438:Alcohols