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Please login to access the full content or check if you have access via Method 1: Pyridin-3-ols from (2-Azaallenyl)pentacarbonylchromium Complexes, ­Alkynes, and Carbon Monoxide

DOI: 10.1055/sos-SD-015-00002

Spitzner, D.Science of Synthesis, (20051538.

Condensation of the aminocarbenechromium complex (Fischer complex) 106 with benz­aldehyde, using titanium(IV) chloride/triethylamine as catalyst, gives the (2-azaallen­yl)pentacarbonylchromium complex 107 (Scheme 38).[‌165‌] This complex cyclizes under neutral conditions at 80°C (sealed tube) with an alkyne to give a mixture of the corres­ponding pyridin-3-ol 108 and 1H-pyrrole 109;[‌166‌] carbon monoxide is provided by the ­pentacarbonylchromium moiety. (Trimethylsilyl)acetylene (R1=H; R2=TMS) gives mainly the corresponding pyridine, whereas most other alkynes give a mixture or only the 1H-pyrrole.

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