Diastereoselective synthesis of (2R,4S,5S)‐(+)‐5‐(2,2‐dichloroacetamido)‐ 4‐(4‐nitrophenyl)‐2‐aryl‐1,3‐dioxanes

(2R,4S,5S)‐(+)‐5‐(2,2‐Dichloroacetamido)‐4‐(4‐nitrophenyl)‐2‐aryl‐1,3‐dioxanes 3–8 were synthesized with high diastereoselectivity and good yields. The structures of acetals were determined and the configurations were confirmed by 2D‐NMR (NOESY) and X‐ray crystallographic analysis.     

Efficient Synthesis of 1,3‐Dithiol‐2‐one Derivatives via 4,5‐Bis(dibromomethyl)‐1,3‐dithiol‐2‐one

A series of 1,3‐dithiol‐2‐one derivatives via [4 + 2] Diels–Alder cycloaddition reaction of 4,5‐bis(dibromomethyl)‐1,3‐dithiol‐2‐one with vinyl‐substituted compounds have been synthesized. Structures of all the newly synthesized compounds are well supported by spectral data such as ¹H‐NMR, MS, and elemental analysis. The structures of IVf and IVg have been analyzed by X‐ray crystallography.     

PPh3‐catalyzed knoevenagel condensation: A facile synthesis of 5‐(1H‐indol‐3‐yl)Meth‐ ylene)‐2, 2‐Dimethyl‐1, 3‐Dioxane‐4, 6‐dione,and their N‐alkyl derivatives by using peg‐600 as the reaction medium

Triphenylphosphine (TPP) has been utilized as a novel and efficient catalyst for the Knoevenagel condensation of indole‐3‐carboxaldehydes 1(a–e) , 1‐methyl‐1H‐indole‐3‐carboxaldehydes 4(a–e) , and 1‐ethyl‐1H‐indole‐3‐carboxaldehydes 6(a–e) with the active methylene compound, that is, meldrum's acid ( 2 ), to afford substituted derivatives 5‐((1H‐indol‐3‐yl) methylene)‐2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione 3(a–e) , 2,2‐dimethyl‐5‐((1‐methyl‐1H‐indol‐3‐yl)methylene)‐1,3‐dioxane‐4,6‐dione 5(a–e) , and 2,2‐dimethyl‐5‐((1‐ethyl‐1H‐indol‐3‐yl)methylene)‐1,3‐dioxane‐4,6‐dione 7(a–e) , respectively, in ethanol medium at RT just within 1 h in excellent yields. The products 3(a–e) were reacted independently with alkylating agents, that is, DMS and DES in the presence of PEG‐600 as an efficient and green solvent, to afford the corresponding N‐substituted methyl and ethyl derivatives 5(a–e) and 7(a–e) , respectively. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:41–48, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20750     

Synthesis of 4H‐1,3‐oxathiin‐4‐ones by reaction of α‐diazo‐β‐diketone with thiones

A series of 2,2‐disubstituted 5,6‐diphenyl‐4H‐1,3‐oxathiin‐4‐ones was synthesized by cycloaddition of thiones with benzoylphenylketene, which was generated by the thermal Wolff rearrangement of 2‐diazo‐1,3‐diphenyl‐1,3‐propanedione. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:630–632, 2001     

Synthesis and conformational analysis of a small meta‐cyclophane,bis(5‐carbomethoxy‐1,3‐phenylene)‐14‐crown‐4

A small cyclophane, bis(5‐carbometh‐oxy‐1,3‐phenylene)‐14‐crown‐4 (BCMP14C4, 3 ) and its diacid, bis(5‐carboxy‐1,3‐phenylene)‐14‐crown‐4 ( 4 ), were synthesized and characterized. The solid‐state molecular structures of 3 and 4 were determined by X‐ray crystallography as ladder or stepped conformations in which the two aromatic rings are antiparallel to each other without overlap and the ethylene tethers both take trans‐conformations. Diester 3 is formed in the lowest cyclization yield (under the same reaction conditions) and exhibits the highest melting point compared to its larger ring (20‐, 26‐ and 32‐membered) analogs. In CD₂Cl₂ solution, diester 3 exists predominantly as a nonplanar gauche–gauche structure as deduced by H NMR studies. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:48–54, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20393     

New Transformation of 1,3‐Oxathiolane‐2‐thione into 1,3‐Dithiolan‐2‐one via Polymerization and Depolymerization

This article deals with the cationic and anionic depolymerization of polydithiocarbonate, which was synthesized by cationic polymerization of 5‐phenoxymethyl‐1,3‐oxathiolane‐2‐thione ( 1 ) using methyl triflate as the initiator. The cationic depolymerization of the obtained polymer was carried out in the presence of 5–20 mol‐% of methyl triflate or triflic acid catalyst in chlorobenzene at 60 °C for 96 h to afford 4‐phenoxymethyl‐1,3‐dithiolan‐2‐one ( 2 ) in 35–83% yield. The anionic depolymerization of the polymer was carried out in the presence of 5 mol‐% of triethylamine or potassium tert‐butoxide at 20 °C for 24 h to afford 2 in 85–100% yield.     

Original recyclization of S‐phenacyl derivatives of 4‐acylamino‐2‐mercapto‐1,3‐oxazoles and their analogues

Readily accessible acylamino(chloro)acetophenones, if treated with sodium rhodanide and α‐halogenocarbonyl compounds, provide 4‐acylamino‐5‐aryl‐2‐mercapto‐1,3‐oxazole derivatives which undergo recyclization on heating in polyphosphoric acid to give substituted 1,3‐thiazol‐2(3H)‐ones or 1,3‐thiazolidin‐2,4‐diones containing 2‐alkyl(aryl)‐5‐aryl‐1,3‐oxazol‐4‐yl residues at the N³ atom. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:432–437, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20317     

Peculiar reaction of N2‐acyl derivatives of 2‐aryl‐5‐hydrazino‐1,3‐oxazole‐4‐carbonitriles with the lawesson reagent

Easily accessible N²‐acyl derivatives of 2‐aryl‐5‐hydrazino‐1,3‐oxazole‐4‐carbonitriles react peculiarly with the Lawesson reagent. In addition to thionation, the reaction involves a recyclization to afford new substituted 2‐(5‐amino‐1,3‐thiazol‐4‐yl)‐1,3,4‐thiadiazoles. Their structure is corroborated spectroscopically and by the X‐ray diffraction method. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:782–785, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20413     

Synthesis of 2,3‐dihydro‐1,3‐thiazin‐4(1H)‐ ones and their remarkably facile recyclization to 2,3‐dihydropyrimidin‐4(1H)‐ones

Functionalized 2,3‐dihydro‐1,3‐thiazin‐4(1H)‐one derivatives have been synthesized by cyclocondensation of 3‐alkyl(aryl)amino‐2‐cyano‐3‐mercaptoacrylamides with aldehydes and ketones under acidic catalysis. 6‐Alkyl(aryl)amino‐5‐cyano‐2,3‐dihy‐ dro‐1,3‐thiazin‐4(1H)‐ones, when treated with a dilute solution of potassium hydroxide, are converted into the potassium salts of isomeric compounds, 1‐alkyl‐ (aryl)‐5‐cyano‐6‐mercapto‐2,3‐dihydropyrimidin‐ 4(1H)‐ones. Alkylation of the latter with dimethyl sulfate in situ furnishes 1‐alkyl(aryl)‐6‐alkylthio‐5‐ cyano‐2,3‐dihydropyrimidin‐4(1H)‐ones, whereas boiling them in ethanol with an excess of hydrochloric acid leads to starting 2,3‐dihydro‐1,3‐thiazin‐4(1H)‐ones. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:426–436, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20129     

Reaction of cyclic imidates with α,β‐unsaturated esters: Synthesis of new pyrrolo[2,1‐b]‐1,3‐oxazine and pyrido[2,1‐b]‐1,3‐oxazine derivatives

The cycloaddition reaction of cyclic imidates, 2‐benzyl‐5,6‐dihydro‐4H‐1,3‐oxazines 1a , 1b , 1c , 1d , 1e , 1f , with dimethyl acetylenedicarboxylate 2 , trimethyl ethylenetricarboxylate 4 , or dimethyl 2‐(methoxymethylene)malonate 6 afforded new fused heterocyclic compounds, such as methyl (6‐oxo‐3,4‐dihydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐ylidene)acetates 3a , 3b , 3c , 3d , 3e , 3f (71–79%), dimethyl 2‐(6‐oxo‐3,4,6,7‐tetrahydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐yl)malonates 5b , 5c , 5d , 5e , 5f (43–71%), or methyl 6‐oxo‐3,4‐dihydro‐2H,6H‐pyrido[2,1‐b]‐1,3‐oxazine‐7‐carboxylates 7a , 7b , 7c , 7d , 7e , 7f (32–59%), respectively. In these reactions, 1a , 1b , 1c , 1d , 1e , 1f (cyclic imidates, iminoethers) functioned as their N,C‐tautomers (enaminoethers) 2 to α,β‐unsaturated esters 2 , 4, and 6 to give annulation products 3 , 5 , and 7 following to the elimination of methanol, respectively. J. Heterocyclic Chem., (2011).     

Cyclization vs. Elimination Reactions of 5‐Aryl‐5‐hydroxy 1,3‐Diones: One‐Pot Synthesis of 2‐Aryl‐2,3‐dihydro‐4H‐pyran‐4‐ones

2‐Aryl‐2,3‐dihydro‐4H‐pyran‐4‐ones were prepared in one step by cyclocondensation of 1,3‐diketone dianions with aldehydes. The use of HCl (10%) for the aqueous workup proved to be very important to avoid elimination reactions of the 5‐aryl‐5‐hydroxy 1,3‐diones formed as intermediates. The TiCl₄‐mediated cyclization of a 2‐aryl‐2,3‐dihydro‐4H‐pyran‐4‐one with 1,3‐silyloxybuta‐1,3‐diene resulted in cleavage of the pyranone moiety and formation of a highly functionalized benzene derivative.     

New domino‐reaction for the synthesis of N4‐(5‐aryl‐1,3‐oxathiol‐2‐yliden)‐2‐phenylquinazolin‐4‐amines and 4‐[4‐aryl‐5‐(2‐phenylquinazolin‐4‐yl)‐1,3‐thiazol‐2‐yl]morpholine

The model morpholine‐1‐carbothioic acid (2‐phenyl‐3H‐quinazolin‐4‐ylidene) amide (1) reacts with phenacyl bromides to afford N⁴‐(5‐aryl‐1,3‐oxathiol‐2‐yliden)‐2‐phenylquinazolin‐4‐amines (4) or N⁴‐(4,5‐diphenyl‐1,3‐oxathiol‐2‐yliden)‐2‐phenyl‐4‐aminoquinazoline ( 5 ) by a thermodynamically controlled reversible reaction favoring the enolate intermediate, while the 4‐[4‐aryl‐5‐(2‐phenylquinazolin‐4‐yl)‐1,3‐thiazol‐2‐yl]morpholine ( 8 ) was produced by a kinetically controlled reaction favoring the C‐anion intermediate. ¹H nmr, ¹³C nmr, ir, mass spectroscopy and x‐ray identified compounds ( 4 ), ( 5 ) and ( 8 ).     

A regioselective 1,3‐dipolar cycloaddition of 2‐arylidene‐1‐tetralones with DPNI

Synthesis of a series of novel 1,3‐diphe nyl‐4‐arylspiropyrazolines[5.2¹]‐1¹‐tetralones has been accomplished in good yield by regioselective 1,3‐dipolar cycloaddition of diphenylnitrilimine with (E)‐2‐arylidene‐1‐tetralones. X‐ray crystal structure analysis of one of the products 4b confirms the structure and the regiochemistry of cycloaddition. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 331–336, 1999     

Reaction of 6‐Methyl‐2‐Thiouracil and 6‐Phenyl‐2‐Thiouracil with Chloro‐β‐Dicarbonyl and Bromo‐β‐Dicarbonyl Compounds and Their Nitrile Analogs

Derivatives of 2‐methylidene‐1,3‐dihydropyrimidin‐4‐ones 2a , 2b , 2c , 2d , 2e , 2f , 2g were synthesized by interaction of 6‐methyl‐2‐thiouracil and 6‐phenyl‐2‐thiouracil 1a , 1b with some activated halogenides: diethyl bromomalonate, ethyl 2‐chloro‐3‐oxobutanoate, ethyl 2‐bromocyanoacetate, 2‐bromo‐5,5‐dimethylcyclohexan‐1,3‐dione, and bromomalononitrile. The boiling of 1a with ethyl 2‐bromocyanoacetate in mixture of ethanol and EtONa results in intramolecular cyclization and formation of thiazolo[3,2‐a]pyrimidin‐5‐one 3 . Interaction of 1a with 3‐chloropentane‐2,4‐dione and 2‐bromo‐1,3‐diphenylpropane‐1,3‐dione yielded corresponding S‐substituted thiopyrimidines 4a , 4b . In general, the products of 1b S‐alkylation are less prone to sulfur extrusion. Reaction of 1b with diethyl bromomalonate in the absence of EtONa stops at the S‐alkylation step, while in the presence of EtONa in ethanol or PPh₃ in dioxane 2‐(ethoxycarbonylmethyl)thio‐6‐phenyl‐1,3‐dihydropyrimidin‐4(1H)‐one 6 is formed exclusively. Molecular structure and crystal structure of 2‐(1,1‐diethoxycarbonylmethyliden)‐6‐methyl‐1,3‐dihydropyrimidin‐4(1H)‐one 2a are discussed.     

Cationic ring‐opening polymerization of novel 1,3‐dehydroadamantanes with various alkyl substituents: Synthesis of thermally stable poly(1,3‐adamantane)s

Cationic ring‐opening polymerizations of 5‐alkyl‐ or 5,7‐dialkyl‐1,3‐dehydroadamantanes, such as 5‐hexyl‐ ( 4 ), 5‐octyl‐ ( 5 ), 5‐butyl‐7‐isobutyl‐ ( 6 ), 5‐ethyl‐7‐hexyl‐ ( 7 ), and 5‐butyl‐7‐hexyl‐1,3‐dehydroadamantane ( 8 ), were carried out with super Brønsted acids, such as trifluoromethanesulfonic acid or trifluoromethanesulfonimide in CH₂Cl₂ or n‐heptane. The ring‐opening polymerizations of inverted carbon–carbon bonds in 4–8 proceeded to afford corresponding poly(1,3‐adamantane)s in good to quantitative yields. Poly( 4–8 )s possessing alkyl substituents were soluble in 1,2‐dichlorobenzene, although a nonsubstituted poly(1,3‐adamantane) was not soluble in any organic solvent. In particular, poly( 8 ) exhibited the highest molecular weight at around 7500 g mol^?1 and showed excellent solubility in common organic solvents, such as THF, CHCl₃, benzene, and hexane. The resulting poly( 4–8 )s containing adamantane‐1,3‐diyl linkages showed good thermal stability, and 10% weight loss temperatures (T₁₀) were observed over 400 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4111–4124     

Synthesis of 9‐[2‐(2‐hydroxymethyl‐2‐methyl‐, ‐(2‐acetoxymethyl‐2‐methyl‐, ‐(2,2‐di(hydroxymethyl)‐, and ‐(2,2‐Di(acetoxymethyl)‐1,3‐dioxan‐5‐yl)ethyl] derivatives of guanine and 2‐aminopurine

Synthesis of 9‐[2‐(2‐hydroxymethyl‐2‐methyl‐, ‐(2‐acetoxymethyl‐2‐methyl‐, ‐(2,2‐di(hydroxymethyl)‐, and ‐(2,2‐di(acetoxymethyl)‐1,3‐dioxan‐5‐yl)ethyl] derivatives of guanine and 2‐aminopurine, 2–9 , has been accomplished in seven to eight step sequences from readily available 1‐(tert‐butyldiphenylsilyloxy)‐acetone, 1,3‐di(tert‐butyldiphenylsilyloxy)acetone, and the diol 10 . Formation of cyclic ketals 11 and 12 was carried out successfully under an acidic condition using a catalytic amount of methanesulfonic acid along with excess anhydrous copper(II) sulfate in toluene. Subsequent reactions of desilylation, acetylation, hydrogenolysis, and bromination afforded the key intermediates 19 and 20 , which were coupled with 2‐amino‐6‐chloropurine to produce the purine compounds 21 and 22 in good yields. Guanine derivatives 2–5 were obtained from 21 and 22 by hydrolysis and acetylation, while the dechlorination and hydrolysis of 21 and 22 yielded the 2‐aminopurine compounds 6–9 .     

Cycloaddition of bis‐1,3‐dipolar reagents to 1,3‐diarylprop‐2‐en‐1‐ones

Bis pyrazolines and isoxazolines were prepared by 1,3‐dipolar cycloaddition of benzene‐1,3/1,4‐dicarboxaldehyde dihydrazones and dioximes to 1,3‐diaryl‐prop‐2‐en‐1‐ones. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:379–383, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10169     

Synthesis of 4‐phosphonyl‐1,3‐dithioles and 1,3‐dithiolanes via the Bu3P‐CS2 adduct

New one‐pot syntheses of 2‐arylidene‐4‐phosphonyl‐1,3‐dithioles or 1,3‐dithiolanes were realized by reaction of the tributylphosphine‐carbon disulfide adduct with phosphonyl alkynes or phosphonyl alkenes and aldehydes in moderate yields. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:633–637, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10053     

Synthesis of (4Z)‐4‐(Arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones by the Reaction of Ethyl (2Z)‐3‐Aryl‐2‐isothiocyanatoprop‐2‐enoates with Organolithium Compounds

A convenient one‐pot method for the preparation of (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones 2 and 3 from ethyl (2Z)‐3‐aryl‐2‐isothiocyanatoprop‐2‐enoates 1 , which can be easily prepared from ethyl 2‐azidoacetate and aromatic aldehydes, has been developed. Thus, these α‐isothiocyanato α,β‐unsaturated esters were treated with organolithium compounds, including lithium enolates of acetates, to provide 5‐substituted (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones, 2 , and 2‐[(4Z)‐(4‐arylmethylidene)‐5‐ethoxy‐2‐thioxo‐1,3‐oxazolidin‐5‐yl]acetates, 3 .     

2,2‐Dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl benzoate, 2,2‐dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate and 5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate

The crystal structures of 2,2‐dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl benzoate, C₁₃H₁₅NO₅, (I), 2,2‐dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate, C₁₃H₁₄ClNO₅, (II), and 5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate, C₁₁H₁₁NO₅, (III), have been determined in order to gain insight into the conformational preference of α‐benzoyloxynitroso. Unfavourable 1,3‐diaxial interactions force (I) and (II) to crystallize in the 2,5 twist‐boat conformation, whereas compound (III), lacking this destabilizing interaction, crystallizes in the chair conformation.