6%, while m-aminophenol was used as material, tetrahydropyran as hydroxyl shielding effect agent, ethyl bromide as ethyl reactant and dimethylsulfate as methyl reactant.

4-Chloro-6-phenyl-2-(2-oxopropyl)tetrahydropyran was obtained unexpectedly by the Prins reaction of 4-methyl-1,8-nonadiene-4,6-diol and benzaldehyde in the presence of indium trichloride in methylene chloride at room temperature.

9%,while m-aminophenol is used as reactant,tetrahydropyran as hydroxyl shielding effect agent,acetic anhydride as acyl protection reactant and amidogen mono-substituted alternative reactant,ethyl bromide as ethyl reactant,dimethylsulfate as methyl reactant.

As an effective protection for hydroxy group in alcohols and phenols,the methods for the formation of tetrahydropyran ether and its cleavage employed in the last 15 years are reviewed.

K_2CO_3 as the base,aromatic aldehyde,malononi- trile and 5,5-dimethyl-1,3-cyclohexanedione were condensed to form tetrahydrobenzo[b]-γ-pyran derivatives in a solvent-free one-pot process under grinding.

One-Pot Synthesis of 2-Amino-3-cyano-4-aryl-7,7-dimethyl-5-oxo- 4H-5,6,7,8-tetrahydrobenzo[b]pyran in Aqueous Medium;