V, R= C, H, VI, R= nC, HS in theory to vary alkyl substituents at each position of the cyclobutenone ring. Thus, substitution at the 2 position can be controlled by varying the acetylene used, 14 substituents at the 4 position may be changed by varying the and substitution at the 3 position may be accomplished via the Grignard reaction, Using sodium methoxide in methanol, substitution at the 3 position procecds further to give 3, 3- ...
