Regiospecific synthesis of 2‐substituted furanonaphthoquinones

The naturally‐occurring furanonaphthoquinones 1a‐d have been synthesized from 3‐furancarboxylic acid and 2,3‐dimethoxybenzaldehyde via the Birch reduction‐elimination.     

Transformations of isomeric naphthopyranones. The synthesis of substituted β-naphthyl-α,β-dehydro-α-amino acid derivatives

The opening of the pyranone ring in 2H-naphtho[1,2-b]pyran-2-one derivative (1) and 3H-naphtho[2,1-b]-pyran-3-one derivatives 8 and 20 with nucleophiles afforded 3-(naphthyl-1)- and 3-(naphthyl-2)propenoates (substituted β-naphthyl-α,β-dehydro-α-amino acid derivatives) 7, 13, 14, 15, 24 , and 35 .     

Zn(OAc)2•2H2O‐catalyzed synthesis of α‐aminophosphonates under neat reaction

A series of novel α‐aminophosphonates have been prepared by one‐pot three‐component condensation in the presence of a zinc acetate (Zn(OAc)_2•2H₂O) catalyst at 50°C under solvent‐free conditions with excellent yields. The major advantages of the present method are high yields, a short reaction time, and solvent‐free reaction conditions. Their antimicrobial activity was evaluated, and some of them showed significant activity. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:160–165, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20765     

The synthesis and crystal structure of α-perthionaphthoatopyridinecopper(I) dimer Cu2(α-C10H7CSS2)2(Py)2

The title compound has been synthesized by the reaction of α-dithionaphthoic acid with CuCl₂ in pyridine or by recrystallizing Cu₄(α-C₁₀H₇CSS₂)₄ ? 1/2CS₂ in a mixture of pyridine and alcohol. The structure of the title compound is determined by a single-crystal X-ray diffraction analysis. The crystal belongs to triclinic space group with unit cell parameters: a=7.085(2)Å, b= 8.672(3)Å and c=13.598(5)Å; a=92.40(3)°, β=102.59(4)° and γ=105.67(4)°; V=780.6Ų; Z=1. The structure was refined to R=0.058 for 2390 reflections. The molecule of the title compound sits on a center of symmetry. The shorter Cu—Cu bond length (2.606Å) shows considerable interaction between copper atoms. If the Cu—Cu interaction is ignored, the neighbouring S and N atoms are coordinated to copper atom in a configuration of distorted tetrahedron.     

Reactions of tetrahydro-as-triazine-3(2H)-thiories with α, β-difunctional compounds

The results of allowing tetrahydro-as-triazine-3(2H)-thiones to react with various α,β-diiunctional compounds, such as, α-bromoethyl p-toluenesulfonate, chloroacetaldehyde, α-bromophenylacet-uldehyde, phenaeyl bromide, chloroacetonitrile, α-bromophenylaeelonitrile, and α-cyanobenzyl p-toluenesulfonate are discussed. These condensations give either a 5H-thiazolo[3,2-b]-as-triazine or a 2H-thiazolo[2,3-c]-as-triazine.     

Diels-alder reaction of 2(1H)-pyridones acting as dienes

Diels-Alder reactions between N-phenylmaleimide, acting as the dienophile, and 2(1H)-pyridones having a methoxy or a chloro substituent, were carried out, under atmospheric and high pressure conditions, to give the corresponding isoquinuclidine derivatives. Stereoselectivity of the Diels-Alder reactions was studied using molecular orbital calculations.     

The reaction of α,β-unsaturated aldimines with benzofuroxan

Benzofuroxan reacts with imines derived from crotonaldehyde and cinnamaldehyde, to form 2-imino-methylquinoxaline 1,4-dioxides.     

Reactions of β-heteroatom substituted α,β-unsaturated ketones with dimethylsulfonium methylide

β-Alkoxy- and β-alkylthio α,β-unsaturated ketones react with dimethylsulfonium methylide (DMSM) to give a furan, while β-anilino α,β-unsaturated ketones give the pyrrole. β,β-Bis(alkylthio) α,β-unsaturated ketones react with DMSM to afford the methylene inserted products, λ,λ-bis(alkylthio) β,λ-unsaturated ketones.     

The synthesis of 1-substituted-2-(β-dimethylaminoethyl)benzimidazoles

2-(β-Dimethylaminoethyl)benzimidazoles have been prepared by the reduction of the corresponding 2-benzimidazole-N,N-dimethylacetamides. Condensation of ethyl cyanoacetate with N-benzyl or phenyl-o-phenylenediamines led to N-cyanoacetyl-N'-substituted-o-phenylenediamines, the structure of which were assigned from u.v. and n.m.r. data. An improved synthesis of benzimidazole - 2 - acetic acid derivatives, from substituted ethyl acetimidates and o-phenylenediamines, is described. Dimerisation of 1-phenyl-benzimidazole occurs in the presence of phenyllithium.     

Lipophilic Functionalized Cobyrinic-Acid Derivatives. Part 1. Cobester α-monoacids (α,α,α,β,β,β-hexamethyl α-hydrogen Coα, Coβ-dicyanocobyrinates)

The four α,α,α, β,β,β,-hexamethyl α-hydrogen Coα, Coβ-dicyanocobyrinates 2b, d–f , with a free b-, d-, e-, and f-propionic-acid function, respectively, were prepared by partial hydrolysis of heptamethyl Coα, Coβ-dicyanocobyrinate (cobester; 1 ) in aqueous sulfuric acid. The cobester monoacids 2b, d–f were obtained as a ca. 1:1:1:1 mixture which was separated. The monoacids were purified by chromatography and isolated in crystalline form. The position of the free propionic-acid function was determined by an extensive analysis of 2b, d–f using 2D-NMR techniques; an analysis of the C,H-coupling network topology resulted in an alternative assignment strategy for cobyrinic-acid derivatives, based on pattern recognition. Additional information on the structure of the most polar of the four hexamethyl cobyrinates, of the b-isomer 2b , was also obtained in the solid state from a single-crystal X-ray analysis. Earlier structural assignments based on 1D-NMR spectra of the corresponding regioisomeric monoamides 3b, d–f (obtained from crystalline samples of the monoacids 2b, d–f ) were confirmed by the present investigations.     

Convenient synthesis of some 2‐substituted 4(3H)‐quinazolinone derivatives

A series of 2‐substituted‐4(3H)‐quinazolinones 13‐20 has been synthesized in good yields using the reaction of double lithiated 2‐methylquinazolinone‐4 with a variety of aromatic aldehydes. They have been easily transformed in high yields into the corresponding 2‐substituted conjugated derivatives 21‐28 bearing terminal aryl groups by F₃CCOOH mediated dehydration.     

Reaction of α,β-unsaturated acid chlorides with β-diketones. Synthesis of 4,6,7,8-tetrahydro-2H-1-benzopyran-2,5(3H)-diones

Reaction of an α,β-unsaturated acid chloride with the anion of 5,5-dimethyl-1,3-cyclohexane-dione ( 2 ) gives either the enol ester ( 4 ) or a cyclized product ( 5 ), depending upon the reaction conditions. When the acid chloride is in excess, the ester is obtained. When the anion is in excess and the acid chloride is acryloyl or crotonyl, the cyclized product is obtained. A similar cyclized product ( 9 ) was formed from acryloyl chloride and an excess of the anion of 4-hydroxy-6-methyl-2-pyrone ( 8 ).     

Short synthesis of tryptophane and β-carboline derivatives by reaction of indoles with N-(diphenylmethylene)-α,β-didehydroamino acid esters

The ethylaluminum dichloride catalyzed Michael-type addition of indoles 1a-h to the N-(diphenylmethylene)-α,β-didehydroamino acid esters 2a-c allows a new synthesis of β-methyltryptophanes 41,m and a new route for 1,1-diphenyl-3-carbalkoxy-1,2,3,4-tetrahydro-β-carbolines 5a-m.