Controlled/“Living “Radical Polymerization of(-)-Menthyl Methacrylate

The atom transfer radical polymerization(ARP)of (-)-menthyl methacrylatc((-)-MnMA) mediated by CuCl/bipyridine and ethy1 2-bromopropionate or 1-phenylethyl bromide in THF system has been studied.The dependence of the specific rotation on molecular weight and the CD of Poly((-)-MnMA) thus obatined was investigated.     

A computational study of stereospecifity in the thermal elimination reaction of menthyl benzoate in the gas phase

This paper reports a theoretical study, at the B3LYP/6–31 + G(d,p) and M05‐2X/6–31G + (d,p) levels, on the thermal decomposition of menthyl benzoate (2‐isopropyl‐5‐methylcyclohexyl benzoate). It undergoes a unimolecular first‐order elimination to give 3‐menthene (1‐isopropyl‐4‐methylcyclohexene), 2‐menthene (3‐isopropyl‐6‐methylcyclohexene), and benzoic acid. We studied two possible mechanisms trying to explain the formation of 2‐ and 3‐menthene, via six‐membered or four‐membered cyclic transition states. Rate constants were calculated at two temperatures, 587.1 and 598.6 K, and they agree well with the experimentally determined values. We verify that 3‐menthene is the product mainly formed at both temperatures. The progress of the reactions has been followed by means of the Wiberg bond indices. Intrinsic reaction coordinate (IRC) calculations have been carried out to verify that the localized transition state structures connect with the reactants and products and also to verify that the parent compound, menthyl benzoate, is taking the cis‐configuration needed in the reaction. Copyright © 2009 John Wiley & Sons, Ltd.     

新型对称烷基咪唑离子液体介质中酶催化合成l-乙酸薄荷酯

设计合成三种新型对称烷基咪唑六氟磷酸盐离子液体——1,3-二正丁基咪唑六氟磷酸盐([DnBIM][PF6]), 1,3-二异丁基咪唑六氟磷酸盐([DiBIM][PF6])和1,3-二仲丁基咪唑六氟磷酸盐([DsBIM][PF6]). 以脂肪酶pseudomonas cepacia催化l-薄荷醇和乙酸酐的酯化过程为模型反应, 分别考察不同介质中酶的活性、反应性和稳定性, 结果表明作为反应介质三种新型离子液体均优于经典离子液体1-正丁基-3-甲基咪唑六氟磷酸盐和有机溶剂正己烷. 在三种新的离子液体中, [DiBIM][PF6]具有最好的亲生物性而被选择作为模型反应介质. 此外, 影响l-薄荷醇转化率的各种因素(包括反应温度、底物投料比、离子液体用量和含水量)及酶的重复利用性也被详细研究. 在最佳反应条件下, l-薄荷醇转化率达到97.4%, 酶促反应速度、平衡转化率和半衰期分别是正己烷中的12.7, 4.6和15.1倍. 脂肪酶重复使用10次后催化活性没有明显减少. 由于三种新型离子液体互为同分异构体, 以上事实还表明除憎水性和亲核性以外离子液体的空间构型也是影响酶行为的一个重要因素.     

1,5-苯并硫氮杂-α,α-二甲基-β-内酰胺衍生物的合成、表征及晶体结构

利用异丁酸乙酯、异丁酸异丙酯、异丁酸薄荷醇酯和LDA作用形成烯醇锂盐 ,然后和 1,5 苯并硫氮杂反应 ,得到了 6个新的 1,5 苯并硫氮杂 α ,α 二甲基 β 内酰胺衍生物 .通过元素分析、红外光谱、核磁共振氢谱和质谱对其结构进行了表征 .用X射线单晶衍射测定了 1a的晶体结构 .晶体为三斜晶系 ,P1- 空间群 ,晶胞参数为 :a =0 92 99( 3 )nm ,b =1 0 13 4( 3 )nm ,c =1 2 45 5 ( 4 )nm ,α =98 45 7( 5 )° ,β =10 6 14 3 ( 5 )° ,γ =10 3 843 ( 5 )° ,V =1 0 65 7( 6)nm3 ,Z =2 ,Dc=1 2 95Mg/m3 ,F( 0 0 0 ) =44 0 ,μ =0 175mm-1,R1=0 0 40 6,wR2 =0 10 64 .     

Synthesis and Characterization of (–)‐Menthyl Containing N‐Alkyl Cycloimmonium Salts

The reaction of 4‐phenyl‐2‐aminothiazole or 2‐amino pyridine with α‐bromo acetic (–)‐menthyl ester ( 2c ) yields new N‐alkyl cycloimmonium bromides ( 1c , 3 ) with the chiral (–)‐menthyl substituent, which were isolated and fully characterized by ¹H and ¹³C NMR spectroscopy for the first time. In addition, starting from 4‐phenyl‐2‐aminothiazole, two further N‐alkyl cycloimmonium bromides ( 1a , 1b ) were prepared. The molecular and crystal structures of all three thiazole derived N‐alkyl cycloimmonium bromides ( 1a – c ) were determined by single‐crystal X‐ray diffraction. In all cases the crystal structures are dominated by N–H ··· Br hydrogen bonds, which results in the formation of an extensive hydrogen bonded network in the crystal. Interestingly, in all structures S ··· Br^– distances shorter than the sum of the van der Waals radii are observed.     

Optically active helical polymer from radical polymerization of menthyl vinyl ketone

Menthyl vinyl ketone (MVK) was radically polymerized to obtain a polymer with excess of one‐handed helical sense. Like as the anionically polymerized poly‐MVK, the radically polymerized poly‐MVK also kept stable one‐handed helical conformation in solvent. The optical rotation and the circular dichroism signal intensity of the radically polymerized poly‐MVK were larger than that of the anionically polymerized poly‐MVK. The molecular weight of the radically polymerized poly‐MVK was much larger than that of the THF‐soluble part of the anionically polymerized poly‐MVK. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

高立体选择性地合成薄荷基溴和新薄荷基溴

薄荷基溴和新薄荷基溴是一类非常有用的不对称合成中间体。以L-薄荷醇为原料,通过与不同的溴化剂反应高立体选择性地得到薄荷基溴和和新薄荷基溴。当L-薄荷醇与盐酸和无水溴化锌反应时高立体选择性地得到薄荷基溴,当L-薄荷醇与三溴化磷反应时高立体选择性地得到新薄荷基溴.     

L-薄荷基-β-D-半乳糖苷的合成新方法

首次报道了硫代糖苷法合成L-薄荷基-β-D-半乳糖苷。半乳糖经过乙酰化、硫代、脱乙酰基和苯甲酰基化反应,转变成供体异丙基-2,3,4,6-四-O-苯甲酰基-1-硫-β-D-半乳糖苷。该供体与L-薄荷醇偶联及脱保护,获得了L-薄荷基-β-D-半乳糖苷。所有的产品通过NMR、MS等方法进行了结构表征。通过TG方法,探讨了所合成的L-薄荷基-β-D-半乳糖苷的热失重过程。     

Synthesis,structure and properties of new chiral liquid crystalline monomers and homopolysiloxanes containing menthyl groups

The synthesis is described of four new chiral liquid crystalline monomers (M₂–M₅ ) and their corresponding side‐chain homopolysiloxanes (P₂–P₅ ) containing menthyl groups. Chemical structures were characterised using FT‐IR or ¹H NMR spectra, and specific optical rotations were evaluated with a polarimeter. The phase behaviour and mesomorphic properties of the new compounds were investigated by differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy, UV/visible/NIR spectrocopy and X‐ray diffraction. The monomers and homopolymers with more aryl segments showed noticeably lower specific optical rotation value. The monomers M₂–M₅ formed a cholesteric or blue phase when a flexible spacer was inserted between the rigid mesogenic core and the terminal menthyl groups by reducing the steric effect. M₂–M₅ revealed enantiotropic cholesteric phase. Moreover, M₂ also exhibited a monotropic smectic A (SmA) phase, and M₄ also exhibited a cubic blue phase on cooling. The selective reflection of light shifted to the long wavelength region with increasing rigidity of the mesogenic core for M₂–M₅ . P₂–P₅ exhibited SmA phases, and the mesogenic moieties were ordered in smectic orientation with their centres of gravity in planes. Melting or glass transition temperature and the clearing temperature increased, and the mesophase temperature range widened with increasing rigidity of the mesogenic core.