1: 50 percent / 60-120 mesh silica gel / diethyl ether / 21 °C 2: 1.) sulfuryl chloride, pyridine / 1.) ether, 21 deg C, 2 h; 2.) ether, 21 deg C, 2 h 3: 83 percent / n-butyllithium / hexane; diethyl ether / 1 h / 0 °C View Scheme

silica gel in diethyl ether T=21°C;

2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride in various solvent(s) T=80°C; 0.5 h; Bu3Sn. effect in SH2 displacement of alkoxy radicals from sulphur, exo cyclization; Rate constantMechanism;

2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride in various solvent(s) T=80°C; 0.5 h; Bu3Sn. effect in SH2 displacement of alkoxy radicals from sulphur, exo cyclization; Rate constantMechanism;

Multi-step reaction with 2 steps 1: 50 percent / 60-120 mesh silica gel / diethyl ether / 21 °C2: 1.) sulfuryl chloride, pyridine / 1.) ether, 21 deg C, 2 h; 2.) ether, 21 deg C, 2 h