An Organocatalytic Synthesis to Chiral Pyrano[2,3-d]pyrimidines Through [3+3] Annulation of 1,3-dimethyl-barbituric acid with 2-(1-Alkynyl)-2-alken-1-ones

Abstract: A novel efficient enantioselective [3+3] annulation to chiral pyrano[2,3-d]pyrimidines from 1,3-dimethyl-barbituric acid and 2-(1-Alkynyl)-2-alken-1-ones is reported here. A thiourea-tertiary amine bifunctional catalyst was synthesized and applied in the construction of the framework of Chiral Pyrano[2,3-d]pyrimidines. It was found that the reaction proceeded swimmingly to procure target products in moderate to good yields and enantioselectivities. The strategy benefits from broad scope of 18 examples. The drop of temperature is beneficial to the improvement of enantiometric excesses. The steric hindrance play an important role in the performance of the devise reaction.

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