Instituto de Química-Universidade de São Paulo, Av. Prof. Lineu Prestes 748, CP 26077, CEP 05513-970 São Paulo SP, Brazil.
Molecules. 2013 Sep 10;18(9):11100-30. doi: 10.3390/molecules180911100.
The iodine-catalyzed Prins cyclization of homoallylic alcohols and aldehydes was investigated under metal-free conditions and without additives. Anhydrous conditions and inert atmosphere are not required. The reaction of 2-(3,4-dihydronaphthalen-1-yl)propan-1-ol and 21 aldehydes (aliphatic and aromatic) in CH₂Cl₂ in the presence of 5 mol % of iodine gave 1,4,5,6-tetrahydro-2H-benzo[f]isochromenes in 54%-86% yield. Under similar conditions, the Prins cyclization of six alcohols containing an endocyclic double bond (primary, secondary, or tertiary) led to dihydropyrans in 52%-91% yield. The acyclic homoallylic alcohols gave 4-iodo-tetrahydropyran in 29%-41% yield in the presence of 50 mol % of iodine. This type of substrate is the main limitation of the methodology. The relative configuration of the products was assigned by NMR and X-ray analysis. The mechanism and the ratio of the products are discussed, based on DFT calculations.
在无金属条件下且无需添加任何助剂的情况下，研究了碘催化的偕丙醇和醛的普林斯环化反应。该反应无需无水条件和惰性气氛。在碘（5 mol%）存在下，2-（3,4-二氢萘-1-基）-1-丙醇和 21 种醛（脂肪族和芳香族醛）在 CH₂Cl₂中反应，以 54%-86%的收率得到 1,4,5,6-四氢-2H-苯并[f]异色烯。在类似条件下，含有中环双键（伯、仲或叔）的六种醇的普林斯环化反应以 52%-91%的收率得到二氢吡喃。在碘（50 mol%）的存在下，非环偕丙醇以 29%-41%的收率得到 4-碘四氢吡喃。该类底物是该方法的主要限制因素。根据 NMR 和 X 射线分析确定了产物的相对构型。根据 DFT 计算讨论了反应机理和产物的比例。
