Unexpected 1,3‐Dipolar Cycloaddition Reaction of Thiazolo[3,2‐a]pyrimidine Derivatives and Nitrilimine

The 1,3‐dipolar cycloaddition reactions of nitrilimine with thiazolo[3,2‐a]pyrimidine derivatives was investigated. Bis‐cycloadducts were obtained through a domino 1,3‐dipolar cycloaddition/ring‐opening/ring‐opening/1,3‐dipolar cycloaddition processes. The structures of the products were characterized thoroughly by NMR, IR, MS, elemental analysis together with X‐ray crystallographic analysis.     

Synthesis of 1,5‐Benzodiazepine Derivatives Containing 1,2,3‐Triazole Moiety via 1,3‐Dipolar Cycloaddition Reaction

A series of 1,5‐benzodiazepine derivatives were synthesized by the reaction of 1,5‐benzodiazepine containing 1,2,3‐triazole moiety with benzohydroximinoyl chlorides at room temperature. The structural identities of these novel compounds were confirmed on the basis of IR, ¹H NMR, mass spectral and elemental analysis data, and by X‐ray crystallographic analysis of a typical example of the new class of 1,5‐benzodiazepine analogs.     

Design and Synthesis of Novel Quinoline Tethered Tricyclic 1,5‐Benzothiazepine Derivatives via 1,3‐Dipolar Cycloaddition Reaction

A series of novel substituted‐[1,2,4]oxadiazolo[5,4‐d][1,5]benzothiazepine derivatives contain quinoline ring 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l were synthesized by the reaction of benzothiazepines 4a , 4b , 4c and substituted‐benzohydroximinoyl chlorides through the 1,3‐dipolar cycloaddition reaction in the presence of Et₃N at room temperature. The structures of the obtained adducts were elucidated by MS, IR, ¹H NMR, and elemental analyses. In addition, the structures of 5e were further confirmed by X‐ray single crystal diffraction study.     

Synthesis of New Bis‐1,2,4‐Oxadiazoline Derivatives via 1,3‐Dipolar Cycloaddition Reaction

A series of novel bis‐oxadiazoline derivatives 4 was synthesized via 1,3‐dipolar cycloaddition reaction of bis‐aldimines 3 , and nitrile oxides generated in situ from various benzohydroximinoyl chlorides in the presence of Et₃N. The target products were confirmed by IR, ¹H‐NMR, and mass spectrometry.     

Efficient Synthesis of [1,3]Oxazino[3,2‐f]phenanthridine Derivatives by a Novel 1,4‐Dipolar Cycloaddition Involving a Phenanthridine–Dimethyl Acetylenedicarboxylate Zwitterion and Aromatic Aldehydes

An efficient synthesis of [1,3]oxazino[3,2‐f]phenanthridine derivatives via a three‐component reaction of phenanthridine, dimethyl acetylenedicarboxylate (DMAD), and aromatic aldehydes is described. This novel method is complementary to the classical Huisgen 1,4‐dipolar cycloaddition in that it is well‐suited to the preparation of [1,3]oxazino[3,2‐f]phenanthridines.     

An Efficient Synthesis of New Dispiropyrrolidine Derivatives via Three‐Component 1,3‐Dipolar Cycloaddition Reaction

A series of new dispiropyrrolidine derivatives were synthesized via the three‐component 1,3‐dipolar cycloaddition reaction of azomethine ylides generated in situ by the decarboxylative condensation of acenaphthenequinone and sarcosine or l ‐thioproline with 5‐benzylidene‐1,3‐dimethylpyrimidine‐2,4,6‐trione. The structures of the products were identified by IR, ¹H‐NMR, and HRMS spectra.     

1,3-偶极环加成合成新型含2-苯基-1,2,3-三唑基-1,5-苯并硫氮杂(艹/卓)噁二唑并合衍生物

α,β-不饱和酮(1a～1e)与邻氨基苯硫酚反应, 得到含2-苯基-1,2,3-三唑基1,5-苯并硫氮杂(艹/卓)(2a～2e), 然后以此化合物为原料同1,3-偶极子氧化腈"现场"发生1,3-偶极环加成, 合成出一系列含2-苯基-1,2,3-三唑基的1,2,4-(口恶)二唑并合的1,5-苯并硫氮杂衍生物(3a～3j). 产物经元素分析、 IR、 1H NMR及MS加以确证.     

Synthesis of Novel 1,2,4‐oxadiazoline Derivatives Containing Quinoline Moiety by 1,3‐Dipolar Cycloaddition

A series of novel 1,2,4‐oxadiazoline derivatives containing 2‐(1,2,4‐triazol‐1‐yl)quinoline were synthesized by the reaction of imines with benzohydroximinoyl chlorides in the presence of Et₃N via 1,3‐diplolar cycloaddition reaction. The structures of the target compounds were confirmed by IR, ¹H NMR, MS, elemental, and X‐ray crystallographic analysis.     

Synthesis of Novel Spiro Thiazolotriazole Derivatives via 1,3‐Dipolar Cycloaddition of Azomethine Ylide

The 1,3‐dipolar cycloaddition of azomethine ylide generated in situ from isatin and sarcosine to 5‐arylmethylidene thiazolo[3,2‐b][1,2,4]triazol‐6(5H)‐ones afforded novel 1′‐methyl‐4′‐aryldispiro[indole‐3,2′‐pyrrolidine‐3′,5″‐[1,3]thiazolo[3,2‐b][1,2,4]triazole]‐2,6″ (1H)‐diones in moderate yields. The structures of all the products were characterized thoroughly by NMR, infrared spectroscopy (IR), mass spectroscopy (MS) elemental analysis together with X‐ray crystallographic analysis.     

Synthesis and Characterization of Novel 1,2,4‐oxadiazoline Derivatives Containing Pyrazole Moiety by 1,3‐Dipolar Cycloaddition

A series of novel pyrazolyl‐oxadiazoline derivatives bearing 1,2,4‐triazole moiety 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p were synthesized by schiff bases of 3‐methyl‐1‐phenyl?5‐(1,2,4‐triazole‐1‐yl)‐4‐formylpyrazole 3a , 3b , 3c , 3d and various benzohydroximinoyl chlorides in the presence of Et₃N via 1,3‐dipolar cycloaddition reaction. The target products were confirmed by IR, ¹H‐NMR, MS, elemental analysis. In addition, the structure of compound 4d was defined by X‐ray crystallography.     

Synthesis and structure characterization of new [1,2,4]triazolo[5,4‐d][1,5]benzothiazepine derivatives through 1,3‐dipolar cycloaddition reaction

Reaction of 1,5‐benzothiazepines 3 , obtained from chalcones 2 and o‐aminobenzenthiol, with the (phenylhydrazino) chloromethylenecarboxylates 4 in the presence of Et₃N leads to a series of new [1,2,4]triazolo[5,4‐d][1,5]benzothiazepine derivatives 5 . Their structures were established using spectroscopic methods and that of compound 5d was confirmed using X‐ray diffraction analysis. J. Heterocyclic Chem., (2011).     

Synthesis of Novel Spiro Pyrano[2,3‐d]thiazolo[3,2‐a]pyrimidine via 1,3‐Dipolar Cycloaddition of Azomethine Ylide

The reaction involving 4‐phenyl‐octahydro‐pyrano[2,3‐d]pyrimidine‐2‐thione, ethyl chloroacetate and the appropriate aromatic aldehyde yielded 2‐arylmethylidene‐5‐phenyl‐5a,7,8,9a‐tetrahydro‐5H,6H‐pyrano[2,3‐d][1,3]thiazolo[3,2‐a]pyrimidin‐3(2H)‐ones. The 1,3‐dipolar cycloaddition of 2‐arylmethylidene‐5‐phenyl‐5a,7,8,9a‐tetrahydro‐5H,6H‐pyrano[2,3‐d][1,3]thiazolo[3,2‐a]pyrimidin‐3(2H)‐ones with azomethine ylide generated by a decarboxylative route from sarcosine and acenaphthenequinone afforded 4′‐aryl‐1′‐methyl‐5″‐phenyl‐5a″,7″,8″,9a″‐tetrahydro‐2H,5″H,6″H‐dispiro[acenaphthylene‐1,2′‐pyrrolidine‐3′,2″‐pyrano[2,3‐d][1,3]thiazolo[3,2‐a]pyrimidine]‐2,3″‐diones in moderate yields. The structures of the products were determined and characterized thoroughly by NMR, MS, IR, elemental analysis, and X‐ray crystallographic analysis.     

Selective Synthesis Dispiro[indoline‐3,2′‐pyrrolidine‐3′,3″‐quinoline] Derivatives and Spiro[imidazole‐4,3′‐quinoline] Derivatives via 1,3‐Dipolar Cycloaddition Reaction

A new class of spiro compounds as dispiro[indoline‐3,2′‐pyrrolidine‐3′,3″‐quinoline] and spiro[imidazole‐4,3′‐quinoline] have been developed from quinolone derivative adopting modern synthetic methodologies.     

Highly Efficient and Diastereoselective Construction of Tricyclic Pyrrolidine‐Fused Benzo[b]thiophene 1,1‐dioxide Derivatives via 1,3‐Dipolar [3 + 2] Cycloaddition

A rapid and highly efficient 1,3‐dipolar [3 + 2] cycloaddition of nonstabilized azomethine ylides generated in situ with benzo[b]thiophene 1,1‐dioxides as the dipolarophiles has been developed. The efficient method affords tricyclic pyrrolidine‐fused benzo[b]thiophene 1,1‐dioxide derivatives in high to excellent yields (up to 99%) with excellent diastereoselectivities (up to >25:1 dr) under mild reaction conditions. The structure of a typical product was confirmed by X‐ray crystallography.     

A Novel Synthesis of Some 1,4‐Phenylene‐bis‐heterocyclic Derivatives and of Some Pyran,Pyrano[2,3‐c]pyrazole,and Pyrano[2,3‐d]pyrimidine Derivatives [1]

p‐Diacetyl benzene 1 undergoes bromination to afford p‐bromoacetyl phenacyl bromide 2 . Compound 2 reacts with twofold excess of malononitrile to afford 2‐{2‐[4‐(3,3‐Dicyanopropionyl)‐phenyl]‐2‐oxo‐ethyl}‐malononitrile 3 . Compound 3 could be cyclized to afford the 1,4‐phenylene‐bis‐furan derivative 4 . Compound 3 reacts also with a twofold excess of hydrazine hydrate and phenyl hydrazine under dry conditions at RT to afford the bis‐pyrazole derivatives 5a , 5b , respectively. The reaction of 5a , 5b with the same reagents in refluxing dioxane afforded the bis‐pyrazolopyridazine derivatives 7a , 7b , respectively. The azo coupling of compound 3 with arene diazonium salts afforded the bis‐pyrazole derivatives 9a , 9b , 9c . The β‐keto esters 10a , 10b react with benzaldehyde and malononitrile in a one pot synthesis to afford the pyran derivatives 11a , 11b . These latter compounds react with hydrazine hydrate and urea derivatives to afford the pyrano[2,3‐c]pyrazoles 15a , 15b and the pyrano[2,3‐d]pyrimidine derivatives 17a , 17b , respectively.     

Desymmetrization of 1,4‐Pentadien‐3‐ol by the Asymmetric 1,3‐Dipolar Cycloaddition of Azomethine Imines

Desymmetrization of the divinyl carbinol 1,4‐pentadien‐3‐ol was accomplished by the asymmetric 1,3‐dipolar cycloaddition of azomethine imines based on a magnesium‐mediated, multinucleating chiral reaction system utilizing diisopropyl (R,R)‐tartrate as the chiral auxiliary. The corresponding optically active trans‐pyrazolidines, each with three contiguous stereogenic centers, were obtained with excellent regio‐, diastereo‐, and enantioselectivity, with results as high as 99 % ee. This reaction was shown to be applicable to both aryl‐ and alkyl‐substituted azomethine imines. The use of a catalytic amount of diisopropyl (R,R)‐tartrate was also effective when accompanied by the addition of MgBr₂.     

An Approach to the Synthesis of Spiro[indene‐pyridoisoquinoline] Derivatives via 1,4‐Dipolar Cycloaddition of Isoquinoline and Acetylene Esters,and (1,3‐Dihydro‐1,3‐dioxo‐2H‐inden‐2‐ylidene)malononitrile

A concise and efficient approach to the spiro‐tetrahydroisoquinoline derivatives has been developed by 1,4‐dipolar cycloaddition of zwitterions resulting from isoquinoline and acetylene esters and (1,3‐dihydro‐1,3‐dioxo‐2H‐inden‐2‐ylidene)malononitrile in MeCN at room temperature. The significance of this method lies in good yields and ease of product purification, and no inert atmosphere is required. The structures of the products were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme).