HPMV

Note that we have been discussing lamps utilizing 254 nm. photon as an excitation energy. Since we have already discussed HPMV lamps which utilize 254-413 nm radiation to excite phosphors (see above), we are now ready to explore the vacuum-UV region which uses photons generated at 147 nm to 173 nm wavelengths to excite phosphor display devices. These include 2 types, plasma display panels (POP) and Neon Signs. 

DeBoef and co-workers described the aerobic oxidative inter- and intra-molecular coupling of benzoxazole (120) with benzene derivatives in the presence of catalytic amounts of Pd(OAc)2 and heteropolymolybdovanadic acid (HPMV) (Scheme 10.40). Under these conditions, the monoarylated C2 products 121-123 were obtained in moderate to good yields in less than 2 hours extended reaction times led to formation of the undesired 2,3-diarylated products. Problematic coupling partners included anisole (which afforded regiomeric mixtures of the C2 product) and electron-poor or acidic arenes which led to no product formation. Palladation is thought to occur at the more nucleophilic C3 position before migration to the C2 position and biaryl product formation. 

Mn(OAc)3 H20, have been used, but perhaps one of the most unique examples was by DeBoef and co-workers in which they used HPMV as a co-catalyst oxidant to afford high yields in the atylation of benzofurans via GDC reactions (Scheme 6.6). ... 

Scheme 6.6 Aerobic aiylation of benzofurans via Pd-catalyzed CDC with HPMV as the oxidant. ...

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