Gamma-pyrones are prepared by contacting a 3-halo-furfuryl alcohol or a 3-alkoxy-furfuryl alcohol with one equivalent of a halogen, peracid or peroxide oxidant and then heating until hydrolysis of the formed 4-substituted-dihydropyran intermediate is substantially complete. Maltol (2-methyl-3-hydroxy-4H-pyran-4-one) is prepared by this process from 2(1-hydroxyethyl)-3-alkoxy furans or 2(1-hydroxyethyl)-3-halo-furans. Gamma-pyrones are also prepared by contacting the corresponding 3-substituted-2,5-dialkoxy-furfuryl alcohols with acid until conversion to the gamma-pyrones is substantially complete.
Gamma-pyrones是通过将3-卤代基
呋喃基醇或3-烷氧基
呋喃基醇与等量的卤素、过酸或过氧化物氧化剂接触,并加热至形成的4-取代二氢
吡喃中间体的
水解基本完成而制备的。从2(1-羟乙基)-3-烷氧基
呋喃或2(1-羟乙基)-3-卤代
呋喃中,通过这个过程制备了
麦芽醇(2-甲基-
3-羟基-4H-吡喃-4-酮)。Gamma-pyrones也可以通过将相应的3-取代-2,5-二烷氧基
呋喃基醇与酸接触,直到转化为gamma-pyrones基本完成而制备。