Facile Entry to 3,4-Dihydro-1H-pyrrolo[2,1-c][1,4]oxazines through the oxa-Pictet–Spengler Reaction

An intermolecular approach to the construction of 3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazines is reported for the first time using the oxa-Pictet–Spengler reaction. The method involves a sequence of carbon–carbon- and carbon–oxygen-bond formation between a substituted 2-(1H-pyrrol-1-yl)ethan-1-ol and an aldehyde/ketone. p-Toluenesulfonic acid (pTSA) was identified as a suitable catalyst to promote the reaction. The method provides a one-step conversion of various aldehydes/ketones into the corresponding 3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazines. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim