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.
Alcázar
Eva
E
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
Pletcher
Joseph M
JM
McDonald
Frank E
FE
D000438:Alcohols / Q000737:chemistry*; D003500:Cyclization; D007536:Isomerism
D000438:Alcohols