Stereospecific Synthesis of Cyclic Sulfite Esters with Sulfur-Centered Chirality via Diastereoselective Strategy and Intramolecular H-Bonding Assistance

Abstract

Stereospecific synthesis of several cyclic sulfite esters containing three stereogenic centers from enantiopure 1,1,4,4tetraarylbutanetetraols was achieved. Chiral sulfur centers were constructed stereospecifically via a diastereoselective reaction with the assistance of an intramolecular H-bonding interaction. The absolute configuration of the S atom was elucidated by using the corresponding single-crystal X-ray diffraction analysis of the synthesized monochloride cyclic sulfite esters. Furthermore, a crystallographic evidence of the specific intramolecular C(sp 3 )−H•••C Ar weak H-bondings was presented, and its dramatic effect on the 1 H NMR spectral properties was revealed. This intriguing behavior was unambiguously rationalized by different shielding effects of the neighboring phenyl rings. Additionally, the theoretical results obtained on the basis of MP2 calculations fully supported the existence of intramolecular hydrogen bonding interactions being responsible for the observed unique chemical and spectral properties.

Manipulating Supramolecular Chirality and Circularly Polarized Luminescence of Cholesteryl Naphthalimides with Multiple Chiral Domains

“…Supramolecular self-assembly or coassembly, as a common way to construct biological macromolecules, has attracted extensive attention. The supramolecular assembly process is mainly dominated by intermolecular noncovalent weak forces, including π–π stacking, C–H···π, hydrogen-bonding interactions, halogen-bond interactions, metal–ligand coordination, van der Waals force, steric hindrance, CH/HC interactions, and so on. − Through rational design of building blocks and control of assembly environments, it is possible to control highly ordered arrangement of building blocks to form nanostructures with different dimensions, such as nanofibers (1D), , semipermeable membranes (2D), and vesicles (3D). , So far, a variety of building blocks have been developed, such as amino acid derivatives, , metal complexes, aromatic compounds, fullerenes, proteins, and polyhedral oligosilsesquioxanes (POSSs) − to construct multifunctional nanomaterials, which have been applied in drug delivery, catalysis, crystal engineering, synthesis of macromolecules, and other fields.…”

Synthesis and Characterization of (2<i>R</i>,3<i>R</i>)-1,4-Dimethoxyl-1,1,4,4- tetraphenyl-2,3-butanediol: A Recommended Comprehensive Chemistry Experiment

“…有机化学是门实验学科，实验教学一方面使学生对有机化学的理论知识和概念得到验证、充实 和提高，另一方面培养学生独立思考、分析问题、解决问题和创新的能力。随着化学学科的快速发 展，有机合成涉及的化合物结构越来越复杂，官能团种类和数目越来越多，基础有机化学实验开设 的内容难以满足要求 [1,2] ；另一方面，对学生绿色化学素养和科研能力提升的要求也越来越高，这对 有机化学实验教学提出了新的要求。有机化学综合实验的设计与创新成为目前有机化学实验教学关 注的热点问题之一 [3] 。 (2R,3R)-1,4-二甲氧基-1,1,4,4-四苯基-2,3-丁二醇1是一种广泛应用的手性二醇，尤其在手性硼酸 酯化学中表现出色。其衍生的手性硼酸酯性质稳定，便于储存和使用，对反应的耐受性较好，且易 于重结晶纯化处理，作为手性助剂，(2R,3R)-1已成功地应用于不对称环丙烷化、环氧化、3,3-Sigmatropic重排和羰基的烯丙基化反应 [4] 。然而，其制备方法仍停留在三十年多前的合成方案 [5] ：从 天然酒石酸酯出发，通过仲羟基的缩醛保护，酯基的烃基化，游离出的叔羟基的醚化和缩醛的去保 护等5步反应制得(2R,3R)-1， 需要用到2,3-二氯-5,6-二氰基苯醌(DDQ)、 LiAlH 4 、 NaH/MeI等价格昂贵、 操作不便且毒性较大的试剂。2008年，有报道对该合成方案进行改进 [6] ：采用便宜的无机盐溴酸钠 和连二亚硫酸钠代替DDQ，但仍需LiAlH 4 和NaH/MeI等试剂，其制备成本较高、合成操作繁琐且具 有一定的危险性，不适合作为本科教学实验开设。(2R,3R)-1,1,4,4-四苯基丁四醇2是α,α,α',α'-四芳基 -2,2-二甲基-1,3-二氧环戊烷-4,5-二甲醇(TADDOL)的母体化合物 [7] ，其与氯化亚砜的反应表现出高 度的区域选择性和立体选择性 [8,9] 。基于绿色化学理念，设计通过(2R,3R)-2的高度区域选择性反应 制备(2R,3R)-1 [10] ，利用常规试剂甲醇代替了NaH/MeI等甲基化试剂，并避免了DDQ-LiAlH 4 等较昂贵 且具有一定危险性试剂的使用，具有原子经济性高、试剂廉价易得、实验操作简便等特点 [11] 生成的吡啶盐，残余物变为淡黄色固体，抽滤，加入四氢呋喃(10 mL)溶解该固体，再加入2 mol•L −1 的NaOH水溶液(20 mL，注意：配制氢氧化钠溶液时会强烈放热，氢氧化钠溶液具有腐蚀性，避免与 皮肤接触)，剧烈搅拌回流1 h，TLC检测反应完成(V EA /V PE = 1 : 6, R f = 0.2)。用滴管将反应混合物缓 慢滴加到冰水中(200 mL，烧杯盛装)，剧烈搅拌30 min，析出浅黄色固体，抽滤，用95%乙醇重结晶， 抽滤，真空干燥后得到0.14 g白色晶体(2R,3R)-1，产率为62%，熔点：78-80 °C [10]…”