Synthesis of cyclic organic compounds

A method of synthesizing a cyclic organic compound, the method comprising (A) contacting a compound of formula (1) (“compound (1)”):

• R1(H)C=C(H)R2 (1), wherein each R1 and R2 is independently H or (C1-C6) alkyl or substituted (C1-C6) alkyl, or the R1 and R2 are bonded together as R—R— to form a (C1-C4) alkylene or substituted alkylene, with a compound of formula (2) (“compound (2)”):
• wherein R4 is H or (C1-C4)alkyl, in the presence of an effective amount of a sulfonic acid reagent and under reaction conditions sufficient to make a compound of formula (3) (“compound (3)”):
• and/or its oxo/R4 regioisomer, wherein R1, R2, and R4 are as defined above.