ATROPISOMER-SELECTIVE LIGAND-COUPLING REACTIONS OF SULFOXIDES - X-RAYMOLECULAR AND CRYSTAL-STRUCTURES FOR YLETHYL)-2,3-DIHYDRONAPHTHO[2,1-D]ISOTHIAZOL-3-ONE AND (R)(-2-BROMO-1-(TERT-BUTYLSULFINYL)NAPHTHALENE())

1-(Alkyl- or aryl-sulfinyl)naphthalenes activated by electron-withdraw ing substituents at the 2-position undergo substitution reactions on t reatment with Grignard reagents. Evidence suggesting that these transf ormations proceed through ligand-coupling reactions of sigma-sulfurane s is presented. The ligand-coupling reaction of homochiral sulfoxides with 1-naphthylmagnesium bromide furnishes atropisomeric 1,1'-binaphth yls in 60-95% ee. Single-crystal X-ray structure determinations have b een carried out on tho[1,2-b]thiophen-3-yl}amino)-2-methylpropan-1-ol 18 and ylethyl)-2,3-dihydronaphtho[2,1-d]isothiazol-3-one 22, compound s formed through intramolecular nucleophilic and electrophilic attack, respectively, on a neighbouring oxazoline group. The absolute configu ration of (R)-(+)-1-(tert-butylsulfinyl)naphthalene 27 was determined by a single-crystal X-ray study of the 2-bromo derivative 28.