Synthesis of spirocyclic thiazolidinediones using ring-closing metathesis and one-pot sequential ring-closing/cross metathesis

A novel synthetic route to spirocyclic thiazolidinediones is reported by utilizing ring-closing metathesis (RCM). A selective cross metathesis (CM) of N-allyl azaspiro derivatives with different olefins has been demonstrated to prepare substituted azaspiro-[4.4]nonenediones. The X-ray crystal structure of a spirocyclic thiazolidinedione dimer is described, which has been prepared in two steps from thiazolidinedione using a one-pot sequential ring-closing and self metathesis. Cross metathesis proceeds smoothly with both electron rich and poor olefins. The symmetrical bis-thiazolidinedione spirocyclic system can be used as CM coupling partner with olefins. One-pot sequential RCM-CM has been developed for the synthesis of substituted spirocyclic compounds. The methodology allows a quick access to thia-azaspiro-[4.4]nonene and -[4.5]decene-dione ring systems from readily available starting materials which are not otherwise accessible.     

Synthesis of substituted 3-aminospiro-4-but-2-enolides

Previously unknown 3-N-alkylamino-, 3-N,N-dialkylamino-4-but-2-enolides containing spirocyclic moiety have been synthesized by nucleophilic addition of amines at the triple bond of methyl ester of β-(1-hydroxycyclohexyl)propiolic acid or by the reaction of amines with the corresponding 3-methoxy-4-but-2-enolide. N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1330–1335, October, 1999.     

An aldol-based build/couple/pair strategy for the synthesis of medium- and large-sized rings: discovery of macrocyclic histone deacetylase inhibitors

An aldol-based build/couple/pair (B/C/P) strategy was applied to generate a collection of stereochemically and skeletally diverse small molecules. In the build phase, a series of asymmetric syn- and anti-aldol reactions were performed to produce four stereoisomers of a Boc-protected γ-amino acid. In addition, both stereoisomers of O-PMB-protected alaninol were generated to provide a chiral amine coupling partner. In the couple step, eight stereoisomeric amides were synthesized by coupling the chiral acid and amine building blocks. The amides were subsequently reduced to generate the corresponding secondary amines. In the pair phase, three different reactions were employed to enable intramolecular ring-forming processes: nucleophilic aromatic substitution (S(N)Ar), Huisgen [3+2] cycloaddition, and ring-closing metathesis (RCM). Despite some stereochemical dependencies, the ring-forming reactions were optimized to proceed with good to excellent yields, providing a variety of skeletons ranging in size from 8- to 14-membered rings. Scaffolds resulting from the RCM pairing reaction were diversified on the solid phase to yield a 14?400-membered library of macrolactams. Screening of this library led to the discovery of a novel class of histone deacetylase inhibitors, which display mixed enzyme inhibition, and led to increased levels of acetylation in a primary mouse neuron culture. The development of stereo-structure/activity relationships was made possible by screening all 16 stereoisomers of the macrolactams produced through the aldol-based B/C/P strategy.     

Synthesis, glycosidase activity and X-ray crystallography of 3-amino-sugars

The cleavage of two sugar epoxides, methyl 2,3-anhydro-alpha-D-mannopyranoside and 2,3-anhydro-alpha-D-allopyranoside, with amines is presented as a method for preparing a library of 3-amino-sugars (methyl 3-amino-3-deoxy-alpha-D-altropyranosides and methyl 3-amino-3-deoxy-alpha-D-glucopyranosides) as potential glycosidase inhibitors. Several of the altropyranosides were micromolar inhibitors of bovine liver beta-galactosidase and almond beta-glucosidase. X-ray crystal structures were determined for one of the methyl 3-amino-3-deoxy-alpha-D-altropyranosides, 4t, and one of the methyl 3-amino-3-deoxy-alpha-D-glucopyranosides, 6d.     

Chemoenzymatic route to various spirocyclic compounds based on enantiomerically enriched tertiary allylic,homoallylic, and homopropargylic alcohols

A ring closing metathesis (RCM) reaction of dienes and an intramolecular Pauson–Khand (PKR) reaction of enynes derived from tertiary allyl, homoallyl, and homopropargyl alcohol backbones to afford the corresponding spirocyclic dihydrofuran and dihydropyrans and spirocyclic cyclopentenone pyrans, respectively, are described. Cyclopent-2-ene anchored tertiary allyl, homoallyl, and homopropargyl alcohols 1a–c have been efficiently resolved via enzymatic resolution with high ee (up to 90%) with 44%, 40%, and 43% chemical yields, respectively. Moreover, the cyclohex-2-ene anchored tertiary allyl, homoallyl, and homopropargyl alcohols 3a–c have also been resolved in the same manner with high ee (up to 97%) and in 42%, 45%, and 49% chemical yields. Enantiomerically enriched dienes derived from tertiary homoallyl alcohols yield the corresponding enantiomerically enriched spirocyclic dihydropyran derivatives via RCM with 74% and 78% chemical yields and with 90% and 97% ee, respectively. Moreover, enantiomerically enriched enynes derived from tertiary homoallyl alcohols afford the corresponding enantiomerically enriched cyclopentenone pyrans with spirocyclic motifs via PKR with 80% and 81% chemical yields, respectively, and as single diastereomers.     

Synthesis of pyridine fused polycyclic amines using sequential ring-closing metathesis and radical cyclisation reactions

The syntheses of novel pyridine fused polycyclic bridgehead amines are described using sequential ring-closing metathesis (RCM) and 5-exo-trig intramolecular radical cyclisation reactions. Critical to the success of the two sequential steps were the RCM catalyst and/or the nature of the nitrogen atom.     

Aminolysis of glycal-derived allyl epoxides and activated aziridines. Effects of the absence of coordination processes on the regio- and stereoselectivity

The addition of primary and secondary aliphatic amines to glycal-derived allyl epoxides is completely 1,2-regio- and anti-stereoselective, whereas mixtures of the corresponding anti-1,2- [3-N-(substituted-amino) glycals] and anti-1,4-addition products (N-glycosyl amines) are obtained with N-(mesyl)-aziridines. In this way, structural moieties, otherwise difficult to synthesize, are obtained by means of a very simple protocol. The regio- and stereoselectivity observed with epoxides is the consequence of an isomerization process, whereas the result obtained with aziridines is explained by the absence of an effective substrate-nucleophile (amine) coordination.     

钾通道启开剂研究(Ⅰ)─—反式-4-氨基-3-羟基-3,4-二氢-2,2-二甲基-2-氢-1-苯并吡喃类化合物的合成及其心血管活性

通过溴醇两步环氧化法并采用三本基膦脱氧合成了一系列新型的反式－4－氨基－3－羟基-3，4－二氢－2，2－二甲基－2－氢－1－苯并吡喃类化合物，通过IR、NMR、MS和元素分析等手段对其结构进行了确证．研究了其中13个化合物对KCI刺激大鼠胸主动脉条收缩抑制作用，考察了其体外血管扩张活性；还对其中11个化合物进行了S．D．大鼠体内降血压实验．结果表明，所测化合物对低钾刺激引起的收缩均有不同程度的抑制作用，其中化合物Ⅰ1、Ⅰ2、Ⅱ5、Ⅱ6效果较好，部分化合物显示较好的降血压活性．     

2D Naphthalenedisulfonate-cadmiun coordination polymer with 2,4,5-tri（4-pyridyl）-imidazole as a co-ligand： Structure and catalytic property

A new 2D coordination polymer, [Cd（tpim）（1,5-nds）]n （1）, was constructed from 1,5-naphthalenedi- sulfonate （1,5-nds）. 2.4,5-tri（4-pyridyl）-imidazole （tpim） and Cd（CH3COO）2.2H2O, which can be subsequently used to promote the epoxide ring-opening reaction of epoxides and amines with remarkable catalytic activity. In addition, the thermal and luminescent properties of I in the solid state were also investigated.     

Synthesis of Novel Indolo‐Spirocyclic Compounds

In the present work, we succeeded to synthesize the novel indolo‐spirocyclic compounds ( 4 , 5 , 6 , 7 and 11 ) via electrophilic condensation reactions of indoles with carbonyl compounds including different types of ketones, for example, heteroacetyl ketones (3‐acetylindole and 3‐acetylpyridine), cyclohexanone, isatin, cyclohexane‐1,4‐dione, whereas an attempt to prepare the spirocyclic 9 failed. This new idea will open a high prospective for continuous investigations related to the synthesis of novel indolo‐spirocyclic compounds.     

Well‐defined epoxide‐containing styrenic polymers and their functionalization with alcohols

Polymers containing electrophilic moieties, such as activated esters, epoxides, and alkyl halides, can be readily modified with a variety of nucleophiles to produce useful functional materials. The modification of epoxide‐containing polymers with amines and other strong nucleophiles is well‐documented, but there are no reports on the modification of such polymers with alcohols. Using phenyloxirane and glycidyl butyrate as low molecular weight model compounds, it was determined that the acid‐catalyzed ring‐opening of aryl‐substituted epoxides by alcohols to form β‐hydroxy ether products was significantly more efficient than that of alkyl‐substituted epoxides. An aryl epoxide‐type styrenic monomer, 4‐vinylphenyloxirane (4VPO), was synthesized in high yield using an improved procedure and then polymerized in a controlled manner under reversible addition‐fragmentation chain‐transfer (RAFT) polymerization conditions. A successful chain extension with styrene proved the high degree of chain‐end functionalization of the poly4VPO‐based macro chain transfer agent. Poly4VPO was modified with a library of alcohols and phenols, some of which contained reactive functionalities, e.g., azide, alkyne, allyl, etc., using either CBr₄ (in PhCN at 90 °C for 2–3 days) or BF₃ (in CH₂Cl₂ at ambient temperature over 30 min) as the catalyst. The resulting β‐hydroxy ether‐functionalized homopolymers were characterized using size exclusion chromatography, ¹H NMR and IR spectroscopy, and thermal gravimetric analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1132–1144     

Synthesis and Antiviral Properties of Spirocyclic [1,2,3]‐Triazolooxazine Nucleosides

An efficient synthesis of spirocyclic triazolooxazine nucleosides is described. This was achieved by the conversion of β‐D ‐psicofuranose to the corresponding azido‐derivative, followed by alkylation of the primary alcohol with a range of propargyl bromides, obtained by Sonogashira chemistry. The products of these reactions underwent 1,3‐dipolar addition smoothly to generate the protected spirocyclic adducts. These were easily deprotected to give the corresponding ribose nucleosides. The library of compounds obtained was investigated for its antiviral activity using MHV (mouse hepatitis virus) as a model wherein derivative 3 f showed the most promising activity and tolerability.     

Dearomative Intramolecular (4+3) Cycloadditions of Arenes with Epoxy and Aziridinyl Enolsilanes

An intramolecular (4+3) cycloaddition of epoxy and aziridinyl enolsilanes with benzene, naphthalene, and anthracene derivatives is reported. Highly functionalized polycyclic alcohols and amines are generated under relatively mild reaction conditions with yields up to 89 %. Optically enriched cycloadducts are obtained from cycloadditions of enantiomerically pure epoxides and aziridines.     

Zinc(II) perchlorate hexahydrate catalyzed opening of epoxide ring by amines: applications to synthesis of (RS)/(R)-propranolols and (RS)/(R)/(S)-naftopidils

Commercially available zinc(II) perchlorate hexahydrate [Zn(ClO4)2.6H2O] was found to be a new and highly efficient catalyst for opening of epoxide rings by amines affording 2-amino alcohols in high yields under solvent-free conditions and with excellent chemo-, regio-, and stereoselectivities. For unsymmetrical epoxides, the regioselectivity was influenced by the electronic and steric factors associated with the epoxides and the amines. A complementarity in the regioselectivity was observed during the reaction of styrene oxide with aromatic and aliphatic amines: aromatic amines provided amino alcohols from nucleophilic attack at the benzylic carbon as major products whereas aliphatic amines resulted in formation of the amino alcohols through reaction at the terminal carbon atom of the epoxide ring as the major/sole products. Reaction of aniline with various glycidic ethers gave the amino alcohols by regioselective nucleophilic attack at the terminal carbon atom of the epoxide ring as the only/major product. Zinc(II) perchlorate hexahydrate was found to be the best catalyst compared to other metal perchlorates. The counteranion modulated the catalytic property of the various Zn(II) compounds that followed the order Zn(ClO4)2.(6)H2O>Zn(BF4)2 approximately Zn(OTf)2>ZnI2>ZnBr2>ZnCl2>Zn(OAc)2>Zn(CO3)2 in parallelism with the acidic strength of the corresponding protic acids (except for TfOH). The applicability of the methodology was demonstrated by the synthesis of cardiovascular drugs propranolol and naftopidil as racemates and optically active enantiomers.     

Enantioselective total synthesis of the potent antitumor agent (-)-mucocin using a temporary silicon-tethered ring-closing metathesis cross-coupling reaction

The enantioselective total synthesis of the annonaceous acetogenin (-)-mucocin (1) was accomplished using a triply convergent 12-step sequence (longest linear sequence) in 13.6% overall yield. This represents the first application of the temporary silicon-tethered (TST) ring-closing metathesis (RCM) cross-coupling reaction and the enantioselective alkyne/aldehyde addition to the synthesis of a complex annonaceous acetogenin. Moreover, all three fragments required for the coupling reactions are conveniently prepared in 5-6 steps from two readily available enantiomerically enriched epoxides. Finally, this synthesis stimulated the development of a new approach for the construction of 3-hydroxy-2,6-disubstituted tetrahydropyrans, using the bismuth tribromide-mediated reductive etherification reaction, which represents a motif that is prevalent in a wide range of pharmacologically significant natural products.     

螺环季酮酸衍生物的合成及生物活性研究

为了寻求新颖的螺环季酮酸先导化合物,以3 -(2,4-二氯苯基)-4-羟基-1-氧杂螺[4.5]癸-3-烯-2-酮为原料,合成了21个螺环季酮酸衍生物,其结构经1H NMR,ESI MS和元素分析确认,并测定了化合物6b的晶体结构.初步生物活性测定表明,此类化合物对朱砂叶螨、蚜虫和粘虫都具有很好的生物活性,尤其是化合物5g和5m对朱砂叶螨的LD50分别为35.12和22.39 mg/L,高于螺螨酯的LD50:45.20 mg/L;化合物5b对蚕豆蚜的LD50为21.90 mg/L,而螺螨酯对蚕豆蚜的LD50为174.13 mg/L.     

Aspects of epoxy resin curing reactions

The progress that has been made in establishing the mechanism of the curing reaction between epoxides and amines, particularly through the use of calorimetric methods (DSC), is discussed. A novel application of tritium-labelled compounds to the study of the reaction of epoxides with imidazoles is also presented. The radiochemical method has produced an enhanced understanding of the reaction mechanism and has given kinetic data in good agreement with DSC measurements.     

Design, synthesis, and biological evaluation of novel fluorinated ethanolamines

The preparation of novel fluorinated allylamines and their use as key fragments for the stereoselective synthesis of hydroxyethyl secondary amine (HEA)-type peptidomimetics is described. Our strategy employs chiral sulfinyl imines as synthesis intermediates, by treatment of hemiaminal precursors with two equivalents of vinylmagnesium bromide. The subsequent oxidation of the allylic amines to the corresponding epoxides was achieved by treatment with methyl(trifluoromethyl)dioxirane. Finally, epoxide ring opening with a range of nitrogen nucleophiles provided a library of HEA-derived peptidomimetics with a phenyldifluoromethylene moiety. The biological evaluation of these derivatives revealed compounds with remarkable BACE1 inhibitory activity. Docking studies revealed the influence of the fluorine atoms in the binding mode of the synthesized ligands. Furthermore, the biological evaluation of our final products and synthesis intermediates led to the discovery of compounds with antimicrobial activity against Mycobacterium and Nocardia species.     

Synthesis of Carbazole Alkaloids by Ring‐Closing Metathesis and Ring Rearrangement–Aromatization

Aprocess for the assembly of carbazole alkaloids has been developed on the basis of ring‐closing metathesis (RCM) and ringrearrangement–aromatization (RRA) as the key steps. This method is based on allyl Grignard addition to isatin derivatives to provide smooth access to 2,2‐diallyl 3‐oxindole derivatives through a 1,2‐allyl shift. The diallyl derivatives were used as RCM precursors to afford a novel class of spirocyclopentene‐3‐oxindole derivatives, which underwent a novel RRA reaction to afford carbazole derivatives. The synthetic sequence to carbazoles was shortened by combining the RCM and RRA steps in an orthogonal tandem catalytic process. The utility of this methodology was further demonstrated by the straightforward synthesis of carbazole alkaloids, including amukonal derivative, girinimbilol, heptaphylline, and bis(2‐hydroxy‐3‐methylcarbazole).     

Y(NO3)3·6H2O catalyzed regioselective ring opening of epoxides with aliphatic, aromatic, and heteroaromatic amines

Yttrium nitrate hexahydrate [Y(NO₃)₃·6H₂O] was found to be an efficient catalyst for selective ring opening of epoxides with aliphatic, aromatic, and heteroaromatic amines at room temperature under solvent-free conditions. The system tolerated a variety of hindered and functionalized epoxides/amines and afforded the desired β-amino alcohols at low catalyst concentration.