A non-stabilized phosphoylide proceeds in a concerted step that does not form an intermediate oxaphosphetane. Instead computational calculations show the two approach one another in a PERPENDICULAR fashion in a concerted manner. Suppose the phosphoylide approaches on the front face of the aldehyde. (A) Note the approach of the aldehyde and unstabilized phosphoylide shown above. Why would the approach below not work? (B) Which of the two approaches will minimize steric hindrance between R2 on the phosphoylide and R1 on the aldehyde with the phosphoylide approaching from the front