Method A General Procedure for Expected Adducts. A 0.10 M solution of dithiane 2 in THF was cooled to-78" C. To this was added an equivalent amount of n-butyllithium. The reaction was stirred at-78" C for 10 min. During this time the solution turns deep red. This was followed by addition of a 2 M THF solution of the appropriate electrophile. The reaction was stirred at-78" C for 15 min. It was then slowly warmed to room temperature. The solution ...