Both 3-(hydroxymethyl)-5-methylsalicylaldehyde and its acetonide condense in the presence of hydrogen chloride in ether to form macrocyclic S(4)-symmetric tetraacetal 2. The reaction is completely oligo- and stereoselective, forming only the tetramer and only the achiral (R,S,R,S)-stereoisomer. Acid-catalyzed equilibration studies and molecular mechanics calculations indicate that the stereoselectivity
3-(羟甲基)-
5-甲基水杨醛及其
丙酮化物在
氯化氢存在下于
乙醚中缩合形成大环S(4)-对称四
缩醛2。该反应是完全低聚和立体选择性的,仅形成四聚体,仅形成四聚体。非手性(R,S,R,S)-立体异构体。酸催化的平衡研究和分子力学计算表明,立体选择性的起源是热力学的。在晶体中,2的鞍形分子形成同轴堆叠,让人联想到品客薯片的堆积。