This molecule must be in so much pain

02 April 2014 - Orgo

biphenylophane nobusue 2014.PNGThis molecule must be in so much sprain. In alkynes the bond angles are usually 180° but here the diacetylene unit makes an angle of 160°. It was synthesised in a simple intramolecular acetylene coupling with copper acetate in a 52% yield. Degradation starts at 70°, triggered by benzyne formation in an intramolecular alkyne - diacetylene 4+2 cycloaddition. The molecule was reported by Shunpei Nobusue et al. in Organic Letters (DOI).