Ring expansion by 2,3-sigmatropic shifts of unstabilized sulfonium ylides. Synthesis of eight- to ten-membered thiacycloalk-4-enes V. Cere, C. Paolucci, S. Pollicino, E. Sandri, and A. Fava The Journal of Organic Chemistry 1978 43 (25), 4826-4831 doi:10.1021/jo00419a024
