1: styrene; (3aS,4R,7S,7aR)-3-acryloyl-4,8,8-trimethylhexahydro-3H-4,7-methano-1,2,3-benzoxathiazole 2,2-dioxide With copper(l) chloride; Grubbs-Hoveyda ruthenium catalyst in ethyl acetate Heating; 2: With sodium periodate; cerium(III) chloride; tetrabutylammonium (meta)periodate in various solvents T=0°C; 3: methanol With methylmagnesium bromide in tetrahydrofuran; dichloromethane T=0°C; Further stages. Title compound not separated from byproducts.;