[Structure cristalline et dichroïsme circulaire de la (1R,3R,4R), (1′R,3′R,4′R)-(bornane 2-one 3-yl)-3′ bornane 2′-one (dicamphre)]

(+)-Camphor reacts in basic media, with N-sulfinylaniline to give, in good yields, dicamphoquinone, which is hydrogenated to dicamphor. Crystals of dicamphor (C20H30O2) belong to space group P2(1), with a = 6.920(1) angstrom, b = 11.207(1) angstrom, c = 11.516(1) angstrom, beta = 99.62(1)0, z = 2, T = 293 K. The final R is 0.044 for 1113 observed reflections. The cohesion of the crystal is the result of van der Waals interactions. The two camphor moieties in this 1.4-diketone are located in chiral positions with respect to each other. The two carbonyl groups form a right handed helix. The Circular Dicroism (CD) spectrum exhibits two Cotton effects of opposite sign and equal intensities in the region of n --> pi* transition: positive at longer wavelength and negative at shorter wavelength. The nature of CD is discussed.