A new type of π-extended 4-bora-3a, 4a-diaza-s-indacene (BODIPY dye), bis (isoindole)- derived benzo [1, 3, 2] oxazaborinine 1, has been synthesized by seven-step procedure from 2-methoxybenzoic acid methyl ester. The benzannulation of the pyrrole ring and the formation of a structurally strained intramolecular B–O ring enable the dye to absorb near- infrared light at ca. 750nm with a molecular extinction coefficient (ε) of ca 8.3× 104M− 1cm ...