Nitrostyrenes as 1,4-CCNO-dipoles: diastereoselective formal [4+1] cycloaddition of indolesElectronic supplementary information (ESI) available: Experimental details, spectral, crystallographic, and computational information (PDF). CCDC 1834625. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8cc07451h

An unusual reactivity of nitrostyrenes in phosphorous acid was discovered, which permits the employment of these readily available synthons as 1,4- CCNO -dipole surrogates in a highly diastereoselective (4+1)-cycloaddition of indoles to afford 4′ H -spiro[indole-3,5′-isoxazoles] in a diastereomerically pure form. An unusual reactivity of nitrostyrenes in phosphorous acid was discovered, which permits the employment of these readily available synthons as 1,4- CCNO -dipole surrogates in a highly diastereoselective (4+1)-cycloaddition of indoles to afford 4′ H -spiro[indole-3,5′-isoxazoles] in a diastereomerically pure form.