[reaction: see text] N-Methyl-4-alkoxy-3-alkynylpyridin-2(1H)-ones readily undergo iodine-promoted 5-endo-heteroannulation under mild conditions to 3-iodofuropyridinium triiodide salts in moderate to good yields. The latter may be dealkylated in situ upon exposure to an iodide anion to provide the corresponding 3-iodofuro[2,3-b]pyridin-4(1H)-ones. The same strategy applies to the formation of furo[2
[反应:见正文] N-甲基-4-烷氧基-3-炔基
吡啶鎓-2(1H)-在中等至良好收率下,容易在温和的条件下经历
碘促进的5-内-异环化成
3-碘呋喃啶鎓三
碘化物盐。后者可在暴露于
碘化物阴离子后原位脱烷基,以提供相应的3-
碘呋喃并[2,3-b]吡啶-4(1H)-。相同的策略适用于
呋喃[2,3-b]
喹啉-4(9H)-one的形成。