Catalytic aza-Wittig Cyclizations for Heteroaromatic Synthesis
journal contributionposted on 19.06.2008 by Stephen P. Marsden, Alison E. McGonagle, Ben McKeever-Abbas
Any type of content formally published in an academic journal, usually following a peer-review process.
The first examples of heterocycle synthesis by iminophosphorane formation/intramolecular aza-Wittig cyclizations that are catalytic in the organophosphorus component are reported. The reaction has been demonstrated in the synthesis of both azine (phenanthridine) and azole (benzoxazole) heterocycles. Catalyst loadings down to 1 mol % have been used with little or no loss in reaction efficiency. The intimate involvement of the phosphine oxide in the catalytic cycle has been verified by in situ infrared spectroscopy.