Novel ether and thioether macrocycles from phthalaldehyde

Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

4-Methoxy-ortho-phthalaldehyde and 4-hydroxy-ortho-phthalaldehyde are potentially useful molecules for fluorimetric analysis of a variety of amines and for the elaboration of complex molecular architectures. Nevertheless, literature generally describes their synthesis in very low yield (below 5%), mainly due to the inefficiency of the last oxidation step. In this paper, we report a reliable synthesis of 4-substituted-ortho-phthalaldehyde analogues in 51% overall yield owing to the addition of a protecting step of the unstable key intermediate 4,5-dihydroisobenzofuran-5-ol. Oxidation and deprotection steps were also studied in order to provide an effective availability of these two dialdehyde compounds that may increase their future applications.

Planarity of substituted pyrrole and furan rings in (3R*, 1′S*, 3′R*)-3-(1′-tert-butylamino-1′H, 3′ H-benzo[c]furan-3′-yl)-2-tert-butyl-2,3-dihydro-1H-benzo[c]pyrrol-1-one

The title structure, (3R*, 1′S*, 3′R*)-3-(1′-tert-butylamino-1′H,3′H-benzo[c]furan-3′-yl)-2-tert-butyl-2,3-dihydro-1H-benzo[c]pyrrol-1-one has been determined at 290 and 150 K by single-crystal X-ray diffraction. The structure comprises two symmetry independent molecules with very similar conformations which differ mostly by orientations of the tert-butyl groups, situated at the periphery of these molecules. The molecules are composed of two parts, the cores of which are isoindolinone and isobenzofuran rings being bound by C–C bonds. The planarities of the pyrrolone and furan rings are compared with the known structures retrieved from the Cambridge Crystal Structure Database. It transpires in the title molecules, the planarity of the carbonyl-substituted pyrrole rings is exceptionally distorted in contrast to the furan rings. This fact is just the opposite of the tendency inferred from the Cambridge Crystal Structure Database. The reason may be the influence of the voluminous tert-butyl group which is attached to the nitrogen of the pyrrole group, as well as short centroid–centroid distances between the carbonyl-substituted pyrrole and furan rings. Cohesion forces between the molecules and their parts are provided by weak interactions only: The packing suggests C–H···O, π–π-electron ring interactions, N–H···π-electron ring as well as C–H···π-electron ring interactions. The structure determination of the title compound, the product of the reaction of o-phthalaldehyde with tert-butylamine, has provided indication about the mechanism of a chemical reaction which resulted in the formation of the title molecule.