Design, Synthesis and Pregnancy-Terminating Activity of 2-Aryl Imidazo[2,1-a]isoquinolines

Introduction Symmetrical trizol bioisosterisms, such as 2-aryl pyrazolo[5,1-a]isoindoles and isoquinolines, pyrazolo- [1,5-a]indoles and quinolines, 2-aryl imidazo[2,1-a]- isoquinolines and isoindoles, 3,5-diaryl-s-triazoles, were shown to be active as non-hormonal post-implantation contragestational agents in various animal species after parenteral administration.1-7 Some compounds had good oral activity.8 Among them, DL204-IT9 [2-(3-ethoxy- phenyl)-5,6-dihydro-s-triazole[5,1-a]isoquinoline…     

l-Proline catalyzed efficient one-pot three-component aza-Diels–Alder reactions on nitrostyrylisoxazoles: a facile synthesis of new isoxazolyl tetrahydroquinolines and isoxazolo[2,3-a]pyrimidines

l-Proline acts as an efficient organocatalyst and found to promote one-pot three-component aza-Diels–Alder reaction of aryl or isoxazole imines formed in situ from aromatic or isoxazoleamines and aromatic aldehydes with nitrostyrylisoxazoles to afford the isoxazolyl tetrahydroquinolines or isoxazolo[2,3-a]pyrimidines, respectively, in excellent yields at ambient temperature under neutral conditions.     

Novel Synthesis of Benzo[a]quinolizines (Pyrido[2,1-a]isoquinolines) by [3+3]-Cyclocondensation of 1-Alkyl-3,4-dihydroisoquinolines with β-Ketoesters

Benzo[a]quinolizines (pyrido[2,1-a]isoquinolines) were synthesized via heterocyclization of 1-alkyldihydroisoquinoline Schiff bases with -ketoesters.     

A facile synthesis of (+)/(−)-pentenomycin I and analogs,and their antimicrobial evaluation

This study reported a stereoselective synthesis of (+)/(+)-pentenomycin I in 4–5 steps through regioselective silylation, optical resolution and dihydroxylation, followed by an olefin formation, from a known racemic cyclopentenone prepared from 2-deoxy-d-glucose. We also accomplished the transformation of a common intermediate into a variety of analogs. In addition, the antimicrobial activities of the pentenomycin analogs were evaluated, which revealed important structural factors of pentenomycins for the antimicrobial activities.     

First total synthesis of the β-carboline alkaloids trigonostemine A,trigonostemine B and a new synthesis of pityriacitrin and hyrtiosulawesine

The total synthesis of four natural products, trigonostemine A, trigonostemine B, pityriacitrin, and hyrtiosulawesine was accomplished. The key intermediates, variously substituted 1-formyl-β-carbolines, were prepared in five steps via a novel synthetic approach using readily available starting materials. These formyl derivatives were then further transformed, providing a general route for the synthesis of the four title alkaloids. The method reported herein represents the first total synthesis of the two trigonostemines and a new pathway to pityriacitrin and hyrtiosulawesine.     

Synthesis of selenium-containing biindolyls and their Diels–Alder reaction toward the synthesis of heteroannulated [a]- and [c]-carbazoles

We reported the first syntheses of 2- and 3-(2-(benzo[b]selenophen-2-yl)-indoles and their Diels–Alder reactions to furnish six unique annulated benzoselenphene carbazoles. This facile route can be used to synthesize selenium-containing biindolyl derivatives that possessed potential pharmaceutical activities.     

Intramolecular Ullmann-type C−N coupling for the synthesis of substituted benzo[4,5]imidazo[1,2-a]pyrrolo[3,4-c]pyridines

An efficient CuI catalyzed intramolecular Ullmann-type C−N coupling reaction is described here. Newly substituted 1H-benzo[4,5]imidazo[1,2-a]pyrrolo[3,4-c]pyridine-1,3,5(2H, 11H)-trione has been easily synthesized from ortho halogenated N-substituted pyrrolo[3,4-c]pyridine-1,3,6(5H)-triones in presence of CuI catalyst and K₂CO₃ base without any ligand. This procedure is based on intramolecular Ullmann-type reaction and provides a proficient method of making fused tetracyclic heterocycles.     

New substituted 2-aminomethyl-2-oxo-2λ5-perhydro-[1,3,2]oxazaphospholo [3,4-a]pyridine: Design,synthesis and antimicrobial activity

The synthesis of a new series of P-heterocyclic compounds, substituted 2-aminomethyl-2-oxo-2λ⁵-perhydro-[1,3,2]oxazaphospholo[3,4-a]pyridine derivatives 8(a-j), was accomplished. A key intermediate, 2-(chloromethyl)-2-oxo-2λ⁵-perhydro-[1,3,2]oxazaphospholo[3,4-a]pyridine (6) was primarily synthesized by the condensation of (±)-2-piperidinemethanol (4) and chloromethylphosphonic dichloride (5); subsequently, it was treated with various heterocyclic amines/benzylamines/aminoacid esters, 7(a-j) to obtain the desired products. The structures of the newly synthesized compounds were elucidated by ¹H, ¹³C, and ³¹P NMR spectroscopy, mass spectra and elemental analyses. The biological potency of title products was investigated by screening in vitro antimicrobial activity. The bio-screening data revealed that most of the synthesized derivatives showed potent growth of inhibition against fungi while compared with bacteria. Particularly, compounds 8c and 8i against bacterial strains, and 8a and 8f against fungi exhibited promising activity.     

One-pot synthesis of pyrrolo[1,2-a]quinoxaline and pyrrolo[1,2-a]pyrazine derivatives via the three-component reaction of 1,2-diamines,ethyl pyruvate and α-bromo ketones

A simple synthetic protocol has been developed involving the three-component reaction between 1,2-diamines, ethyl pyruvate and a-bromo ketones in the presence of Fe Cl3 as a catalyst. A number of pyrrolo[1,2-a]quinoxaline and pyrrolo[1,2-a]pyrazine derivatives were synthesized in excellent yields using this protocol.     

A useful ring transformation route to novel thiazepino[7,6-b]indoles from monochloro-β-lactam-fused 1,3-thiazino[6,5-b]indoles,analogues of cyclobrassinin

The Staudinger ketene-imine cycloaddition reactions of cyclobrassinin phytoalexin analogues 2-aryl-4,9-dihydro-1,3-thiazino[6,5-b]indoles with chloroacetyl chloride as a ketene source were investigated under different conditions. Both β-lactam ring formation and the N-chloroacetylation of the indole moiety took place. The indole N-chloroacetyl group can be easily removed by treatment in the presence of silica gel in methanol at reflux temperature. The selective β-lactam formation can be also achieved in certain cases under milder Staudinger conditions. The treatment of azeto[2,1-b]thiazino[6,5-b]indole-1-one derivatives with sodium ethoxide in ethanol provided the novel thiazepino[7,6-b]indole ring systems in a one-step ring transformation. The structures of the new ring systems were determined by means of IR and NMR spectroscopy.     

Synthesis of chromeno[2′,3′:4,5]imidazo[2,1-a]isoquinolines via a novel domino reaction of isoquinoline-derived immonium salts. Scope and limitations

A one-pot protocol towards chromeno[2′,2′:4,5]imidazo[2,1-a]isoquinoline derivatives via a domino reaction of isoquinoline-derived immonium salts and α-hydroxy aromatic aldehydes is elaborated. The scope and limitations of this reaction is discussed.     

Novel reactions of phosphonium ylides with perhaloalkanes: First examples of halophilic attacks by phosphonium ylides and a facile route to α-haloalkylphosphonium salts

Phosphonium ylides Ph₃PCHR (R = H, CH₃, C₂H₅, n-C₃H₇, n-C₅H₁₁) react readily with perhalofluoroalkanes to afford regiospecifically α-haloalkylphosphonium salts Ph₃P⁺-CHXR Y⁻ (X = I, Br, Cl) in good yields. These reactions reveal a new type of reactivity of phosphonium ylides, i.e., the halophilic attack on CX bonds, and may be useful for the regiospecific synthesis of substituted haloolefins via Wittig reaction.     

A facile one-pot synthesis of new thieno- [2,3-d]pyrimidine-2,4（1H,3H）-dione derivatives

A facile one-pot synthesis of new 3-arylthieno[2,3-d]pyrimidine-2,4(1H,3H)-diones via base-catalyzed cyclocondensation of ethyl 2-amino-4,5-dimethylthiophene-3-carboxylate with aryi isocyanates is described.     

Regioselective synthesis of 2-trivinylsilyl-2Н,3Н-[1,3]thia- and -selenazolo[3,2-a]pyridin-4-ium chlorides

Russian Chemical Bulletin -     

An efficient and general route to the synthesis of diethyl α,α-bromofluorophosphonates

An efficient and general two-step halogenation procedure to prepare diethyl α,α-bromofluorophosphonates was described, which included bromination by PPh₃, 2,3-dichloro-5,6-dicyanobenzquinone (DDQ) and n-Bu₄NBr, and electrophilic fluorination by N-fluorobisbenzenesulfonimide (NFSI). Both aromatic and aliphatic α,α-bromofluorophosphonates could be prepared by this method.     

Copper-catalyzed intermolecular oxidative [3 + 2] cycloaddition between alkenes and anhydrides: a new synthetic approach to γ-lactones

A new copper-catalyzed oxidative [3 + 2] cycloaddition of alkenes with anhydrides using oxygen as the sole oxidant to afford γ-lactones has been developed. This catalyzed cyclization process has a broad substrate scope and affords γ-lactones in good to excellent yields.