SUPPORTING INFORMATION FOR Phosphorus(III)-Mediated Stereoconvergent Formal [4+1]- Cycloannulation of 1,2-Dicarbonyls and o-Quinone Methides: A Multicomponent Assembly of 2,3-Dihydrobenzofurans Kevin X. Rodriguez, Justin D. Vail, and Brandon L. Ashfeld* Department of Chemistry and Biochemistry, University of Notre Dame 251 Nieuwland Science Hall, Notre Dame, IN 46556 bashfeld@nd.edu Contents General S2 Experimental Procedures S2-S15 References S15 1 H and 13 C NMR Spectra S16-S84