无溶剂体系合成1,3-甘油二酯用脂肪酶的筛选及其酯化性质

对不同来源的脂肪酶进行了系统的筛选,并根据位置专一性的差别将脂肪酶分为1,3 特异的、1,3 选择性和非选择性的3类.采用LipozymeRMIM在无溶剂系统中催化甘油、脂肪酸合成1,3 sn 甘油二酯.研究表明脂肪酸、底物醇种类、温度、水分活度对LipozymeRMIM的活力有明显的影响.     

异鸟苷掺入的富鸟嘌呤寡核苷酸的合成

目的改进异鸟苷单体的合成路线,合成异鸟苷掺入的富鸟嘌呤的寡核苷酸.方法以6-O-苄基鸟嘌呤为原料,经环氧开环、催化氢化、水解还原制备异鸟苷,经多步反应后得到异鸟苷亚磷酰化产物,采用固相合成方法合成异鸟苷掺入的富含鸟嘌呤的寡核苷酸.结果与结论经环氧开环能够区域选择性地得到N9取代的单一产物,收率提高到40%,并成功地合成了异鸟苷掺入的富含嘌呤十六聚寡核苷酸.本合成路线具有区域选择性强、路线简单、易操作、收率高等优点.     

沸石负载钒络合物催化剂对烷烃氧化反应的择形选择性

制备了四价钒铬合物 VO(pic) 2 · H2 O催化剂及其分子筛负载型催化剂 VO(pic) 2 -Na Y,并以尿素过氧化氢 CO(NH2 ) 2 ·H2 O2 为氧化剂 ,考察了催化剂对正己烷和正庚烷等烷烃的催化氧化性能。实验结果证明 VO(pic) 2 -Na Y不但具有与 VO(pic) 2 ·H2 O相似的催化氧化活性 ,而且显示出对伯醇 (正构烷烃 )产物有较好的择形选择性。考察了 VO(pic) 2 -Na Y在连续搅拌釜式反应器中进行正己烷和正庚烷的非均相催化氧化反应的催化性能 ,并讨论了不同操作条件对烷烃氧化反应转化率的影响     

Regio- and stereoselective reactions of (S)-(1-methylpyrrolidin-2-yl)methyl allyl sulfide

The synthesis and regioselective reactions of a chiral allyl sulfide, (S)-(+)-(1-methylpyrrolidin-2-yl)methyl allyl sulfide (MAS.1) are described. Remarkable α-regioselectivity was observed in the alkylation of the carbanion of MAS while 1∶3 mixtures of α-and γ-adducts were produced in the addition of the MAS anion to aldehydes. However, a dramatic change of the regioselectivity was witnessed when Lewis acids such as Et₃Al, Et₃B, and Ti(O ⁱ Pr)₄ were used as additives in the addition reaction. In these cases, α-adducts were formed exclusively. A rationale for the change of regioselectivity is provided. And the stereochemical aspect of the addition reaction is also described.     

Regioselectivity significantly impacts microsomal glucuronidation efficiency of R/S-6, 7-, and 8-hydroxywarfarin

1. Coumadin (R/S-warfarin) metabolism plays a critical role in patient response to anticoagulant therapy. Several cytochrome P450s oxidize warfarin into R/S-6-, 7-, 8-, 10, and 4′-hydroxywarfarin that can undergo subsequent glucuronidation by UDP-glucuronosyltransferases (UGTs); however, current studies on recombinant UGTs cannot be adequately extrapolated to microsomal glucuronidation capacities for the liver.

2. Herein, we estimated the capacity of the average human liver to glucuronidate hydroxywarfarin and identified UGTs responsible for those metabolic reactions through inhibitor phenotyping. There was no observable activity toward R/S-warfarin, R/S-10-hydroxywarfarin or R/S-4′-hydroxywarfarin.

3. The observed metabolic efficiencies (V_max/K_m) toward R/S-6-, 7-, and especially 8-hydroxywarfarin indicated a high glucuronidation capacity to metabolize these compounds.

4. UGTs demonstrated strong regioselectivity toward the hydroxywarfarins. UGT1A6 and UGT1A1 played a major role in R/S-6- and 7-hydroxywarfarin glucuronidation, respectively, whereas UGT1A9 accounted for almost all of the generation of the R/S-8-hydroxywarfarin glucuronide.

5. In summary, these studies expanded insights to glucuronidation of hydroxywarfarins by pooled human liver microsomes, novel roles for UGT1A6 and 1A9, and the overall degree of regioselectivity for the UGT reactions.

     

Energetic Materials Based on N-substituted 4(5)-nitro-1,2,3-triazoles

The regularities and synthetic potentialities of the alkylation of 4(5)-nitro-1,2,3-triazole in basic media were explored, and new energetic ionic and nitrotriazole-based coordination compounds were synthesized in this study. The reaction had a general nature and ended with the formation of N1-, N2-, and N3-alkylation products, regardless of the conditions and reagent nature (alkyl- or aryl halides, alkyl nitrates, dialkyl sulfates). This reaction offers broad opportunities for expanding the variability of substituents on the nitrotriazole ring in the series of primary and secondary aliphatic, alicyclic, and aromatic substituents, which is undoubtedly crucial for solving the problems related to both high-energy materials development and medicinal chemistry when searching for new efficient bioactive compounds. An efficient methodology for the separation of regioisomeric N-alkyl(aryl)nitrotriazoles has been devised and relies on the difference in their basicity and reactivity during quaternization and complexation reactions. Based on the inaccessible N3-substitution products that exhibit a combination of properties of practical importance, a series of energy-rich ionic systems and coordination compounds were synthesized that are gaining ever-increasing interest for the chemistry of energy-efficient materials, coordination chemistry, and chemistry of ionic liquids.     

Evaluation of the Synthesis of Soluble Aromatic Cellulose Carbonates of Low Degree of Substitution

The synthesis of soluble cellulose phenyl carbonates of low degree of substitution (DS, as low as 0.3) can be realized by using phenyl chloroformates with reactivity‐controlling moieties in the aromatic ring or by conversion of 6‐O‐triphenylmethyl cellulose. It is assumed that the primary hydroxyl group may yield to cross‐linking during the introduction of the phenyl carbonate moieties. Thus, for the first time soluble cellulose phenyl carbonates of low DS are accessible that are useful for the preparation of novel cellulose derivatives by reaction with nucleophilic reagents in particular amines.     

Investigation of the Polymerization Behavior and Regioselectivity of Fluorene Diamine‐Based Benzoxazines

A series of fluorene diamine‐based benzoxazine monomers are prepared from the reaction of 9,9‐bis‐(4‐aminophenyl)‐fluorene with paraformaldehyde and unsubstituted or substituted phenols. Unsubstituted and substituted phenol‐based benzoxazines show different polymerization behaviors and give polymers with different thermal properties. The ortho and para positions on the phenol for benzoxazines based on phenol and m‐cresol could concurrently participate in the crosslinking reaction during thermal ring‐opening polymerization to form Mannich and methylene bridges at high temperature. The glass‐transition temperature and thermal stability of the resulting polymers are much higher than those of other substituted phenol‐based polybenzoxazines and bisphenol fluorene‐based polybenzoxazines.     

Regioselective Metal‐Free Click Polymerization of Azides and Alkynes

The Cu(I)‐catalyzed azide‐alkyne click polymerization is well developed and broadly applied to the preparation of functional polymers. The removal of copper residues from the resultant polymers is, however, difficult. One way to completely circumvent this difficulty is to develop click polymerization without the use of metallic catalysts, i.e., metal‐free click polymerization (MFCP). Herein, recent efforts towards developing MFCP of activated alkynes and azides, and of activated azides and alkynes, to produce regioregular polytriazoles are summarized, and the properties and applications of the resultant polymers are also briefly discussed.