Towards the synthesis of Palmerolide A: asymmetric synthesis of C1–C14 fragment

The synthesis of a C1–C14 fragment of a marine cytotoxic natural product Palmerolide A is described. The key steps involved in this synthesis are deoxygenative rearrangement of an alkynol followed by an asymmetric dihydroxylation of a diene ester and CBS-reduction.     

Total synthesis of (+)-phomopsolide B

An enantiospecific total synthesis of polyhydroxy δ-pyrone natural product phomopsolide B is accomplished. The main feature of the synthesis is the installation of the required E-olefin by Horner–Emmons–Wordsworth reaction and the formation of the lactone involving Still–Gennari olefination followed by lactonization.     

A convergent approach for the total synthesis of the α-glucosidase inhibitor (−)-panaxjapyne-C

The stereoselective total synthesis of (?)-panaxjapyne-C was accomplished in a convergent fashion. The synthesis utilizes the readily available enantiomers l-(+)-diethyltartrate and d-(?)-diethyltartrate and involves a Cadiot–Chodkiewicz coupling reaction, and an Ohira–Bestmann reaction as the key steps.     

Template synthesis of mesoporous silicas with the use of nanocrystalline cellulose

The porous structure of silica samples prepared via sol–gel synthesis with the use of nanocrystalline cellulose particles as a template has been studied by low-temperature nitrogen adsorption. The influence of the concentration of a nanocrystalline cellulose dispersion, template content in the nanocrystalline cellulose/SiO₂ composite, and the conditions of the sol–gel synthesis on the porous structure of silica has been investigated.     

Efficient synthesis of a side-chain extended diaminodiacid for solid-phase synthesis of peptide disulfide bond mimics

Solid-phase incorporation of diaminodiacids is one of the most effective approaches for synthesis of peptide disulfide bond mimics. One of a limitation of current diaminodiacid toolbox is that only four-atom linkage mimics are available that may not fully meet the activity optimization requirement. In this work, we developed a new diaminodiacid that contains a five-atom thioether (C–C–S–C–C) bridge for the first time. With this diaminodiacid in hand, we successfully obtained oxytocin containing new disulfide bond mimic by solid phase peptide synthesis.     

Four-component stereoselective synthesis of tetracyano-substituted piperidines

Research on Chemical Intermediates - A novel four-component stereoselective synthesis of polysubstituted piperidines is reported. The Knoevenagel–Michael–Mannich cascade of two...     

First stereoselective total synthesis of pectinolide H

The stereoselective total synthesis of bio-active pectinolide H (1) is described. Midland’s asymmetric reduction, Sharpless dihydroxylation reactions are involved in generating the stereogenic centers at C-4′, C-5 and C-1′. Other key steps in the synthesis are Sonogashira cross coupling, Z-selective Still–Gennari olefination, one-pot acetonide deprotection–lactonization, and Lindlar’s reaction. This offers a distinctive strategy for the synthesis of γ-lactones.     

Electrochemical synthesis of 1,3-dimethyl-4-amino-5-formyluracyl in the presence of ammonium chloride

The synthesis of 1,3-dimethyl-4-amino-5-formyluracyl, an intermediate of theophylline synthesis, was studied in an ammonium chloride medium using the electroreduction of 1,3-dimethyl-4-amino-5-nitrosouracyl to a diamino derivative with its further formylation. The electrolysis and formylation conditions were optimized. The reduction of 1,3-dimethyl-4-amino-5-nitrosouracyl was performed under the following conditions: its concentration was 12.0–13.5 %, the cathode was a Kh18N10T stainless steel gauze, the electrolysis was performed in the presence of ammonium chloride, the current density was 7.5–8.0 A/dm², the electrolysis temperature was 40–45°C, and the formylation temperature was 71–72°C. The substance yield of overall formylaminouracyl was 81.2–83.3% and the current efficiency was 62.0–64.5%. The developed process of 1,3-dymethyl-4-amino-5-formyluracyl synthesis was evaluated at a scaled-up laboratory setup with a filter-press cell.     

Industrial catalyst for the selective Fischer–Tropsch synthesis of long-chain hydrocarbons

The results of development of an industrial supported cobalt–silica gel catalyst for the Fischer–Tropsch synthesis are reported. The studies included the selection of a support and the determination of an optimum active component content, a calcination temperature, and the effect of doping with aluminum oxide on the physicochemical and catalytic properties of the Co–SiO₂ system. The catalyst samples were characterized by a set of physicochemical methods. The on-stream stability of the supported cobalt–silica gel catalyst was tested in the continuous mode for 1000 h. In the course of the entire test cycle, the catalyst exhibited stable operation under varied synthesis temperature and gas space velocity, and it can be recommended for industrial applications. The experimental results were used for the preparation of a pilot batch of the catalyst.     

Microwave-assisted synthesis of five-membered S-heterocycles

The development of new strategies for synthesis of five-membered S-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in sulfur-containing five-membered heterocyclic compounds synthesis is presented, focusing on the developments in the last 5–10 years. This contribution covers the literature concerning the total synthesis of five-membered S-heterocycles under microwave and combined effect of microwave and solid-phase.     

Stereoselective synthesis of the C1–C12 fragment of the thuggacins

A concise asymmetric synthesis of the C1–C12 fragment of the antibacterial natural product thuggacins has been achieved. The stereochemistry of this fragment was established efficiently via stereoselective reduction and Evans-aldol condensation. Hanztsch’s method and a Horner–Wadsworth–Emmnons reaction were employed for thiazole formation and the construction of the E-α,β-unsaturated double bond.     

A simplified strategy for the synthesis of dideoxyribonucleotide blocks

The rapid synthesis of dideoxyribonucleotide blocks in 60–85% isolated yields has been achieved by combining the phosphorylation and condensation steps in a sequential reaction series which also allows the recovery of unreacted nucleotides.     

Chichibabin pyridinium synthesis

Chichibabin pyridine synthesis involves the reaction of three aldehydes and ammonia to form 2,3,5-trisubstituted pyridines. This study examined the synthesis of tetrasubstituted pyridinium from aldehydes and an amine hydrochloride in the presence/absence of Pr(OTf)₃. Important insights into the reaction mechanisms of Chichibabin pyridinium synthesis were proposed through the investigation of reaction intermediates along with quantitative GC–MS analysis.     

Stereoselective synthesis of analogs of the macrolactone of isomigrastatin

An approach for the highly stereoselective synthesis of analogs of the macrolactone of isomigrastatin is described. Our optimized strategy is based on a very efficient lactone opening, a Wittig olefination reaction and a ring closing metathesis. The syntheses were accomplished in 10–11 steps and good overall yields.     

Total synthesis of sapinofuranone A from d-ribose

The total synthesis of sapinofuranone A has been achieved starting from naturally occurring carbohydrate d-ribose via a short and high yielding route. The key transformations include Wittig olefination, Ohira–Bestmann reaction, Sonogashira coupling. Finally acetonide deprotection and subsequent lactonization using catalytic amount of hydrochloric acid completed the total synthesis of sapinofuranone A.     

Facile synthesis of a chiral auxiliary bearing the isocyanide group

The synthesis of a chiral isocyanide possessing the easily cleaved menthoxy group is reported. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:561–562, 2001     

Formal synthesis of amphidinin B

An efficient, convergent, and highly stereoselective formal synthesis of amphidinin B (1) is reported herein. In Amphidinin B both C10–C21 (4) and C1–C9 (5) fragments were derived from geraniol 6 and mono-PMB ether of 1,4-butane diol 7 in 19 and 9 steps, respectively. The key steps involved in this synthesis are Sharpless asymmetric epoxidation, Evans aldol, Julia olefination, oxa-Michael, Keck allylation, Mannich reaction, Evans asymmetric alkylation, and Yamaguchi esterification.     

Asymmetric synthesis of furofurans

Furofurans are one of the largest sub-types of classical lignans which have been found to possess a broad range of important biological activities. Tremendous efforts have been directed to develop synthetic methodologies for the synthesis of furofurans, especially in a stereoselective manner, due to their interesting bioactivities associated with the structural and stereochemical complexity. This article summarizes the reports on asymmetric synthesis of furofurans disclosed during the period of 2004–2017.     

Hexabrominated porphyrins in the synthesis of fluorene-containing polyphenols

A new strategy for the synthesis of fluorene-containing polyphenols of porphyrin series by the Suzuki–Miyaura reaction of hexabromoporphyrin and monoboryl derivative of substituted fluorene has been proposed. Several sequential chemical transformations of the prepared porphyrin allowed preparation of polyphenol derivative of the noted compound. Similar polyphenol has been used as a basis for the design of positive photoresists for nanolithography with 13.5-nm exposing radiation, which can produce topological structures with resolution 22–16 nm.     

Ring-expansion approaches for the total synthesis of salimabromide

We describe the evolution of a synthetic strategy for the construction of the marine polyketide salimabromide. Combining a bicyclo[3.1.0]hexan-2-one ring-expansion to build up a functionalized naphthalene and an unprecedented rearrangement/cyclization cascade, enabled synthesis of a dearomatized tricyclic subunit of the target compound. Alternatively, an intramolecular keteniminium [2 + 2]-cycloaddition and subsequent Baeyer–Villiger ring-expansion gave access to the sterically encumbered architecture of salimabromide. Sequential oxidation of the carbon framework finally enabled the total synthesis of this unusual natural product.