The Prins reaction of styrenes with paraformaldehyde or 1,3,5-trioxane in toluene in the presence of cation-exchanged montmorillonite (Mn+-mont), which worked as a Brønsted acid catalyst, at 80 °C produced 4-aryl-1,3-dioxanes selectively in up to 99% isolated yield with a turnover number of up to 5.9 × 102. Among the examined 21 Mn+-monts, Ce3+- and Fe3+-monts were revealed to be quite effective. Regeneration of the catalyst was confirmed with the Ce3+-mont, which could be effectively recycled at least three times. Many lanthanide metal ion-exchanged montmorillonites (Ln3+-monts) were prepared and characterized by X-ray powder diffraction (XRD) and temperature-programmed desorption of ammonia gas (NH3-TPD) methods.
The Catalytic Asymmetric Intermolecular Prins Reaction
作者:C. David Díaz-Oviedo、Rajat Maji、Benjamin List
DOI:10.1021/jacs.1c10245
日期:2021.12.15
Despite their significant potential, catalytic asymmetric reactions of olefins with formaldehyde are rare and metal-free approaches have not been previously disclosed. Here we describe an enantioselective intermolecular Prins reaction of styrenes and paraformaldehyde to form 1,3-dioxanes, using confined imino-imidodiphosphate (iIDP) Brønsted acid catalysts. Isotope labeling experiments and computations
尽管它们具有巨大的潜力,但烯烃与甲醛的催化不对称反应是罕见的,并且以前没有公开过不含金属的方法。在这里,我们描述了苯乙烯和多聚甲醛的对映选择性分子间 Prins 反应以形成 1,3-二恶烷,使用受限的亚氨基-亚氨基二磷酸 ( i IDP) 布朗斯台德酸催化剂。同位素标记实验和计算表明酸活化甲醛低聚物向烯烃中的协同、高度异步添加。对映体富集的 1,3-二恶烷可以转化为相应的光学活性 1,3-二醇,它们是有价值的合成构件。
ZnAlMCM-41: a very ecofriendly and reusable solid acid catalyst for the highly selective synthesis of 1,3-dioxanes by the Prins cyclization of olefins
作者:Manickam Selvaraj、Mohammed A. Assiri、Hari Singh、Jimmy Nelson Appaturi、Ch. Subrahmanyam、Chang-Sik Ha
DOI:10.1039/d0dt04158k
日期:——
formaldehyde (FCHO)) under different reaction conditions to obtain 1,3-dioxanes, which are widely used as solvents or intermediates in organic synthesis. Based on the nature of catalysts used under different reaction conditions, a reasonable plausible reaction mechanism for the Prins cyclization of SE with PFCHO is proposed. Notably, it can be seen from the catalytic results of all catalysts that the W-ZnAlMCM-41(75)
Enantiomerically Pure Poly(oxymethylene) Helices: Correlating Helicity with Centrochirality
作者:Simon Eppacher、Gerald Giester、Jan W. Bats、Christian R. Noe
DOI:10.1002/hlca.200890062
日期:2008.4
A first series of enantiomericallypurehelical oligo(formaldehyde)s (=oligo(oxymethylen)s) 16–20 was synthesized. To induce the chiral uniformity of the helices, we used (1S)-2,2-dimethyl-1-phenylpropan-1-ol (14) to generate the end groups at the α and ω terminus (Scheme 6). Propanol 14 was accessible from its racemate by acetal formation with lactol 12 and separation of the diastereoisomers (Scheme 5)