2-Aminooxazole → N-(4-chloro-2-pyridinyl)-1,3-oxazol-2-amine

HRID 320

Reaction equation

HRID 320 reaction equation
Clc1ccnc(Br)c1.Nc1ncco1>C1COCCO1.CC1(C)c2cccc(P(c3ccccc3)c3ccccc3)c2Oc2c(P(c3ccccc3)c3ccccc3)cccc21.O=C(/C=C/c1ccccc1)/C=C/c1ccccc1.O=C(/C=C/c1ccccc1)/C=C/c1ccccc1.O=C(/C=C/c1ccccc1)/C=C/c1ccccc1.O=C([O-])[O-].[Cs+].[Cs+].[Pd].[Pd]>Clc1ccnc(Nc2ncco2)c1

Participants

7

Reactant 2

HCID 5585212-AminooxazoleHCID 27628362-Bromo-4-chloropyridine

Product 1

HCID 130016260N-(4-chloro-2-pyridinyl)-1,3-oxazol-2-amineYield 7.67%

Reagents, catalysts & solvents 4

HCID 10796Cesium carbonateReagentHCID 6360441,1'-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis(1,1-diphenylphosphine)CatalystHCID 9811564Bis(dibenzylideneacetone)palladiumCatalystHCID 312751,4-DioxaneSolvent

Conditions

Temperature
140 °C

Procedure

Objective: To find out if the 2-bromopyridine is a more efficient coupling partner than the chloro analogue. Pd2(dba)3 (22.89 mg, 0.025 mmol), 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene (43.4 mg, 0.075 mmol), 2-bromo-4-chloropyridine (192 mg, 1.00 mmol), cesium carbonate (652 mg, 2.00 mmol) and oxazol-2-amine (84 mg, 1.00 mmol) were added to an oven dried microwave vial, the vial was capped and placed under an inert atmosphere, dioxane (4 mL) was added and the resulting mixture was heated at 140 °C for 1 h by microwave irradiation under a nitrogen atmosphere. The crude product was purified by flash silica chromatography, elution gradient 0 to 30% EtOAc in heptane. Pure fractions were evaporated to dryness to afford N-(4-chloropyridin-2-yl)oxazol-2-amine (15.00 mg, 7.67 %) as a white solid. Conclusion: A slightly improved yield of the desired product was formed with respect to the 2,4-dichloropyridine substrate, however the difference could not be taken to be significant.

Sources & evidence

ORD record
ord-25a2d29381d0432e90a88d041ce4da72
Source dataset
750 AstraZeneca ELN dataset
Original link
View source

Linked notes

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