A short synthesis of praziquantel

The synthesis of praziquantel ( 1 ), a potent anthelmintic agent, is reported. The synthesis requires five steps and proceeds in 16% yield.     

Remote asymmetric induction in an intramolecular ionic Diels-Alder reaction: application to the total synthesis of (+)-dihydrocompactin

The total synthesis of (+)-dihydrocompactin via an intramolecular ionic Diels-Alder reaction that proceeds with remote stereocontrol is described. This reaction proceeds by an intermediate vinyl-oxocarbenium ion (6), the conformational constraints of which lead to the observed asymmetric induction. The sense of asymmetric induction appears contrasteric and is explained by the proposed reactive conformation shown in Figure 1.     

Metal‐Free Synthesis of Highly Substituted Pyridines by Formal [2+2+2] Cycloaddition under Mild Conditions

The synthesis of pyridines through direct intermolecular cycloaddition of alkynes and nitriles is a contemporary challenge in organic synthesis. A Brønsted acid mediated formal [2+2+2] cycloaddition of heteroalkynes and nitriles was developed that proceeds under mild conditions. This constitutes a modular approach to highly substituted pyridine cores.     

Total synthesis of (+/-)-actinophyllic acid

The first total synthesis of (+/-)-actinophyllic acid (1) is reported. Key steps of this synthesis include an intramolecular oxidative coupling of ketone and malonic ester enolates and an aza-Cope-Mannich rearrangement that assembled the core structure of the natural product's unique ring system. The synthesis was accomplished from di-tert-butyl malonate in 8% overall yield by a concise sequence that proceeds by way of only seven isolated intermediates.     

Sulfuryl Fluoride Mediated Synthesis of Amides and Amidines from Ketoximes via Beckmann Rearrangement

A metal-free and redox-neutral method for Beckmann rearrangement employing inexpensive and readily available SO₂F₂ gas is described. The reported transformation proceeds at ambient temperature and is compatible with a wide range of sterically and electronically diverse aromatic, heteroaromatic, aliphatic and lignin-like oximes providing amides in good to excellent yields. The reaction proceeds through the formation of an imidoyl fluoride intermediate that can also be used for the synthesis of amidines.     

Gold(I)-catalyzed synthesis of dihydropyrans

A trinuclear gold(I)-oxo complex, [(Ph3PAu)3O]BF4, serves as the catalyst for the stereocontrolled synthesis of 2-hydroxy-3,6-dihydropyrans from propargyl vinyl ethers. Importantly, the rearrangement proceeds with excellent diastereoselectivity, and the rearrangement of chiral nonracemic propargyl vinyl ethers proceeds with excellent chirality transfer to furnish enantioenriched pyrans. Additionally, the reaction is amenable to the synthesis of spiroketals from appropriately functionalized precursors. In this case, from a linear precursor, in a single step, the bicyclic spiroketal framework is established with complete stereocontrol over three centers and an alkene functional group in the product.     

Diastereoselective synthesis of pyrrolidines using a nitrone/cyclopropane cycloaddition: synthesis of the tetracyclic core of nakadomarin A

The synthesis of the tetracyclic core of nakadomarin A is described. The core contains all the heterocycles and the required stereocenters found in the natural product and provides a promising route to the target itself. The strategy utilizes a general, diastereoselective pyrrolidine synthesis that proceeds via a homo 3 + 2 dipolar cycloaddition. The scope of this methodology is also described. [structure: see text]     

A concise total synthesis of largazole, solution structure, and some preliminary structure activity relationships

A total synthesis of largazole that proceeds in 8 steps from commercial materials is reported, along with some structure-activity relationships. A combination of NMR studies and molecular modeling have also provided a preliminary picture of the conformation of largazole.     

Convenient Preparation of 2,7,8‐Trimethyl‐6‐hydroxychroman‐2‐carboxylic Acid (γ‐Trolox)

The title chroman is useful in synthesis and as a water‐soluble analog of γ‐tocopherol, a member of the vitamin E family. This new synthesis of γ‐trolox proceeds via selective aromatic demethylation of Trolox, the more easily available 2,5,7,8‐tetramethyl homolog compound. This route is shorter than the previous synthesis, avoids the use of cyanide and methoxybutadiene, and requires no chromatography.     

N-(phenylthio)-epsilon-caprolactam: a new promoter for the activation of thioglycosides

N-(phenylthio)-epsilon-caprolactam (1) has been applied as a new promoter for the activation of thioglycosides. This proceeds by the reaction of 1 with trifluoromethansulfonic anhydride, which subsequently activates the thioglycoside for glycosidic bond formation. Notably, the reaction proceeds efficiently at room temperature and is adaptable to our reactivity-based one-pot oligosaccharide synthesis. [reaction: see text]     

Multistep solid-phase synthesis of an antibiotic and receptor tyrosine kinase inhibitors using the traceless phenylhydrazide linker

The hydrazide group is an oxidatively cleavable traceless linker for solid-phase chemistry. This linker technology was used to develop a multistep solid-phase synthesis of an antibiotic that is active against Mycobacterium tuberculosis. Furthermore, we describe an efficient method for the traceless synthesis of 2-aminothiazoles that display dual inhibitory activity against the receptor tyrosine kinases VEGFR-2 and Tie-2. The synthesis method proceeds through 9 steps on the solid phase and should give access to a much larger library of 2-aminothiazoles, from which a new class of anti-angiogenesis drugs may be developed.     

Facile synthesis of ferrocenylamines in aqueous hydrotropic solution using microwaves

Microwave-assisted synthesis of secondary and tertiary ferrocenylamines is achieved by using an amine exchange reaction between ferrocenylmethyltrimethyl ammonium iodide and aryl amines in aqueous hydrotropic solution. The synthesis proceeds in excellent yields within short reaction times.     

Synthesis of cyclic dimeric methyl morpholinoside—a common synthetic precursor to cyclic dinucleotide analogs

An eight-step synthesis of cyclic dimeric methyl morpholinoside (c-di-MM), a common synthetic precursor to a number of cyclic dinucleotide analogs is reported. The synthesis of c-di-MM proceeds through a morpholine monomer prepared from readily available inexpensive starting materials and culminates with a key macrolactamization reaction to provide the macrocycle in 15% overall yield.     

Synthesis of 1-Arylsulfonylpyrroles

The synthesis of 1-arylsulfonylpyrroles is normally accomplished by the condensation of an arylsulfonyl chloride with pyrrolylpotassium.¹ We wish to report a facile synthesis of 1-arylsulfonylpyrroles which is versatile, proceeds in moderate to good yield and eliminates the necessity of using pyrophoric potassium.     

Direct synthesis of pyrroles from imines, alkynes, and acid chlorides: an isocyanide-mediated reaction

[reaction: see text] A direct synthesis of pyrroles from imines, acid chlorides, and alkynes mediated by isocyanides is reported. This reaction proceeds with a range of each of these three substrates, providing a method to generate families of pyrroles in high yield. Mechanistic studies suggest this process proceeds via the generation of imino analogues of munchnones, which can undergo in situ coupling with alkynes to liberate isocyanate and form the pyrrole product.     

Total synthesis of (−)-cleistenolide

The total synthesis of (−)-cleistenolide, a novel natural product recently isolated from the annonaceae species cleistochlamys kirkii oliver, is described. The synthesis proceeds starting from easily accessible d-manitol using a selective benzoylation, a selective acetonide deprotection, silylprotection and ring-closing metathesis reaction.     

Boc或Cbz保护的L-脯氨醇衍生物的稳定性

近年来,L-脯氨醇衍生物催化的不对称Michael加成反应已经成为手性催化研究领域的热点.而在L-脯氨醇衍生物的合成中,常常涉及到L-脯氨醇氨基的保护.为此,研究了Boc和Cbz保护的脯氨醇衍生物的稳定性,发现Boc保护的L-脯氨醇在羟基被取代为易离去基团时,就变得不稳定,在67℃就发生分子内环合生成化合物y-丁内酯;而Cbz保护的L-脯氨醇衍生物的稳定性要好得多,在140℃且有三乙胺存在时,才会发生类似的分子内环合反应.     

An improved synthesis of 10-isobornylsultone

A modified and improved synthesis of 10-isobornylsultone in three steps and in 81% overall yield starting from (+)-camphor-10-sulfonic acid is described. The synthesis proceeds via methyl sulfonate ester formation, stereoselective reduction and base-catalysed intramolecular cyclisation.     

Synthesis of Vibegron Enabled by a Ketoreductase Rationally Designed for High pH Dynamic Kinetic Reduction

Described here is an efficient stereoselective synthesis of vibegron enabled by an enzymatic dynamic kinetic reduction that proceeds in a high‐pH environment. To overcome enzyme performance limitations under these conditions, a ketoreductase was evolved by a computationally and structurally aided strategy to increase cofactor stability through tighter binding.     

Biomimetic synthesis of (±)-aculeatin D

A practical, efficient and diastereoselective synthesis of the cytotoxic and antiprotozoal compound aculeatin D (1) is described, employing a biomimetic oxidative cyclisation cascade reaction to generate the tricyclic system of the natural product. The synthesis proceeds in ten steps from commercially available 1-tetradecanol.