Orthogonal chromatic selectivity with light activated metathesis catalysts

Efrat Levin, Chemistry, Ben-Gurion University, Beer-Sheva, Israel
Sudheendran Mavila, Chemistry, Ben-Gurion University, Beer-Sheva, Israel
Gabriel Lemcoff, Chemistry, Ben-Gurion University, Beer-Sheva, Israel

Dormant sulfur-chelated ruthenium catalysts for the olefin metathesis reaction have been developed and studied in our research group for the past five years.¹ Upon irradiating latent cis-Naph-S-Ru at a wavelength of 350nm, the complex undergoes a photo-isomerization process to the active trans-Naph-S-Ru isomer.² We have now discovered that irradiation at 250nm does not change the complex. Tris(trimethylsilyl)silyl ether, is a photo-chemically removable protecting group that can be cleaved at 250nm;³ however, it is stable at 350nm. By illuminating triene 1⁴ in the presence of our catalyst we achieved selective product formation depending on the sequence of wavelengths used (Scheme 1). Thus, a proof of concept of a catalytic chromatic orthogonal process⁵ shows that different products may be obtained just by choosing the right order of light irradiation.

¹ A. Ben-Asuly, E. Tzur, C.E. Diesendruck, M. Sigalov, I. Goldberg, N.G. Lemcoff, Organometallics, 2008, 27, 811.

² A. Ben-Asuly, A. Aharoni, C.E. Diesendruck, Y. Vidavsky, I. Goldberg, B.F. Straub, N.G. Lemcoff, Organometallics, 2009, 28, 4652.

³ a) M.C. Pirrung, L. Fallon, J. Zhu, Y.R. Lee, JACS, 2001, 123, 3638. b) M.A. Brook, S. Balduzzi, M. Mohamed, C. Gottardo, Tetrahedron, 1999, 10027.

⁴ Adapted from B. Schmidt and S. Nave, Adv. Synth. Catal., 2007, 349, 215.

⁵ a) C.G. Bochet, Synlett, 2004, 2268. b) C-H Wong, S.C. Zimmerman, Chem. Commun., 2013, 49, 1679.