The birch reduction of heterocyclic compounds. 11. Birch reduction and reductive alkylation of furamides

The Birch reduction-alkylation of some N,N-dialkylfuramides and its application to the useful intermediates for the natural product synthesis are described.     

The birch reduction of heterocyclic compounds. III. Birch reduction-elimination reaction of 2- and 3-furancarboxylic acid derivatives

The Birch reduction of 2-(1-alkoxyalkyl)furan-3-carboxylic acids 1a-f gave 2-alkyl-3-furancarboxylic acids 2a-f with loss of the alkoxyl group in excellent isolated yields.     

Convenient preparations of 2‐alkyl‐5‐oxopyrrolidine‐3‐carboxylic acids

Reduction of the Michael addition products of anions of nitro compounds to dimethyl maleate led to the spontaneous formation of the respective 2‐alkyl‐5‐oxopyrrolidine‐3‐carboxylic acid methyl esters. Conventional hydrolysis of the later gave the desired compounds.     

rac‐(Z)‐Ethyl 2‐bromo‐2‐[(3R,5R)‐3‐bromo‐5‐methyl­tetra­hydro­furan‐2‐yl­idene]acetate

In the title compound, C₉H₁₂Br₂O₃, a (tetra­hydro­furan‐2‐yl­idene)acetate, the double bond has the Z form. In the tetra­hydro­furan group, the relative configuration of the Br atom in the 3‐position and the methyl group in the 5‐position is anti. The compound crystallizes with two independent mol­ecules per asymmetric unit and, in the crystal structure, the individual mol­ecules are linked to their symmetry‐equivalent mol­ecules by C—H⋯O hydrogen bonds, so forming centrosymmetric hydrogen‐bonded dimers.     

Synthesis of 5‐(Arylselanyl)‐2‐(arylsulfanyl)benzoates by [3+3] Cyclocondensation of 3‐(Arylsulfanyl)‐1‐(silyloxy)buta‐1,3‐dienes with 2‐(Arylselanyl)‐3‐(silyloxy)alk‐2‐en‐1‐ones

Functionalized 5‐(arylselanyl)‐2‐(arylsulfanyl)benzoates were prepared by [3+3] cyclocondensation of 3‐(arylsulfanyl)‐1‐(silyloxy)buta‐1,3‐dienes with 2‐(arylselanyl)‐3‐(silyloxy)‐alk‐2‐en‐1‐ones.     

Synthesis and Cyclization of 8‐Formyl‐2‐(phenoxymethyl)quinoline‐3‐carboxylic Acids

A facile synthesis of a series of new quinoline‐8‐carbaldehyde compounds, namely 8‐formyl‐2‐(phenoxymethyl)quinoline‐3‐carboxylic acids ( 4a – 4h ) and 13‐oxo‐6,13‐dihydro[1]benzoxepino[3,4‐b]quinoline‐8‐carbaldehyde ( 5a – 5g ) is described, involving the one‐pot synthesis reaction of ethyl 2‐(chloromethyl)‐8‐formylquinoline‐3‐carboxylate ( 3 ) with substituted phenols followed by the intramolecular cyclization reaction via the treatment with polyphosphoric acid (PPA). Quinoline‐8‐carbaldehydes 4a – 4h and 5a – 5g are novel and their structures were supported by IR, ¹H NMR, ¹³C NMR, MS and elemental analysis.     

Cyclocondensation reactions of heterocyclic carbonyl compounds XII. The double course of cyclization of 3‐(2‐aminobenzyl)‐1,2‐dihydro‐quinoxaline‐2‐one

The cyclocondensation reaction of compound 1 in boiling hydrochloric acid had an unexpected course. Instead of supposed 5,11‐dihydro‐quinoxalino[2,3‐b]quinoline 6a , 2‐(indol‐2‐yl)‐benzimidazole 4 was isolated as the major product.     

Tetrakis­(tetra­hydro­furan‐κO)­lithium mer‐tris­(carbazolyl‐κN)‐trans‐di­chloro(tetra­hydro­furan‐κO)­zirconate

In the title compound, [Li(C₄H₈O)₄][ZrCl₂(C₁₂H₈N)₃(C₄H₈O)], the environment of the Zr atom is pseudo‐octahedral, with the three carbazolyl ligands in a mer configuration. The counter‐ion of the zirconium complex is composed of an Li atom surrounded by four tetra­hydro­furan (THF) mol­ecules. The THF mol­ecule attached to the Zr atom is disordered over two sites, as are two of the THF mol­ecules in the lithium moiety. All bond distances and angles are consistent with those in complexes with similar structural entities. The Zr—N bond distances are 2.2185 (18) and 2.167 (3) Å.     

Synthesis of heterocyclic derivatives of alkyl 2‐(cyanomethyl)‐4‐methyl‐3‐quinolinecarboxylates

The article reports reactions of a series of known alkyl 2‐(cyanomethyl)‐4‐methyl‐3‐quinolinecarboxylates. In the course of the present study the synthesis of new heterocyclic derivatives of alkyl 2‐(cyanomethyl)‐4‐methyl‐3‐quinolinecarboxylates was achieved. J. Heterocyclic Chem., (2011).     

6‐(2‐Hydro­xy­benzoyl)‐5‐(pyrrol‐2‐yl)‐3H‐pyrrolizine

The title compound, 2‐hydroxy­phenyl 5‐(pyrrol‐2‐yl)‐3H‐pyrrolizin‐6‐yl ketone, C₁₈H₁₄N₂O₂, was isolated from the base‐catalyzed 1:2 condensation of 2‐hydroxy­aceto­phenone with pyrrole‐2‐carbaldehyde. The pyrrole N—H and hydroxy­benzoyl O—H groups are hydrogen bonded to the benzoyl O atom. The allyl­ic C=C double bond of the 3H‐pyrrolizine system is located between ring positions 1 and 2, the C atom at position 3 (adjacent to the N atom) being single bonded.     

Synthesis of α‐[5‐(5‐amino‐1,3,4‐thiadiazol‐2‐yl)‐2‐imidazolylthio]acetic acids

The paper describes synthesis and antituberculosis activity of α‐[5‐(5‐amino‐1,3,4‐thiadiazol‐2‐yl)‐imidazol‐2‐ylthio]acetic acids ( 5a,b ). The compounds were tested against Mycobacterium tuberculosis strain H37Rv in comparison to rifampicin. Compounds exhibited low activity (MIC ≤ 6.25 μg/ml, % inhibition ≥ 24).     

Ethyl 2‐form­amido‐2‐(4‐iodo­benzyl)‐3‐(4‐iodo­phenyl)­propionate and ethyl 2‐(3‐bromo­benzyl)‐3‐(3‐bromo­phenyl)‐2‐form­amidopropionate

The title compounds, C₁₉H₁₉I₂NO₃ and C₁₉H₁₉Br₂NO₃, are derivatives of α‐amino­isobutyric acid with halogen substituents at the para and meta positions, respectively. The ethoxycarbonyl and formamide side chains attached to the C_α atom of the mol­ecule adopt extended and folded conformations, respectively. The crystal structures are stabilized by N—H⃛O, C—H⃛O, C—Br⃛O and C—I⃛O interactions.     

Copper(II) triflate-catalyzed reduction of carboxylic acids to alcohols and reductive etherification of carbonyl compounds

A protocol is described for the reduction of carboxylic acids to primary alcohols using 1,1,3,3-tetramethyldisiloxane (TMDS) and a catalytic amount of Cu(OTf)₂. Aliphatic as well as aromatic carboxylic acids are reduced in high selectivity and good yields. TMDS/Cu(OTf)₂ has also been found to be an efficient catalytic reducing system for the preparation of symmetrical ethers from carbonyl compounds under mild conditions.     

Synthesis of 5‐chloro‐2‐methyl‐3‐(5‐methylthiazol‐2‐yl)‐4(3H)‐quinazolinone and related compounds with potential biological activity

Eight new 2‐methyl‐4(3H)‐quinazolinones (8a‐8d, 9c, 9d, 10c, 10d) with one or two chlorine atoms in the benzene ring and a 5‐methyl‐1,3‐thiazol‐2‐yl, 4‐methyl‐1,3‐thiazol‐2‐yl, and 5‐ethyl‐1,3,4‐thiadiazol‐2‐yl substituent in position 3 of the heterocyclic ring were synthesized and characterized. The two step procedure (Scheme 1) utilizes chlorosubstituted anthranilic acids (3a‐3d) and acetic anhydride as the starting materials, with the respective chlorosubstituted 2‐methyl‐4H‐3,1‐benzoxazin‐4‐ones (4a‐4d) as the intermediates. The quinazoline derivatives were characterized by their melting points, elemental analyses and the mass, ultraviolet, infrared, and ¹H and ¹³C nmr spectra. The new compounds are expected to be biologically active.     

Synthesis and herbicidal activity of 2‐(3‐(trifluoromethyl)‐5‐(alkoxy)‐1H‐pyrazol‐1‐yl)‐4‐aryloxypyrimidine derivatives

A series of 2‐(3‐(trifluoromethyl)‐5‐(alkoxy)‐1H‐pyrazol‐1‐yl)‐4‐aryloxypyrimidine derivatives were designed and synthesized. The structures of all the title compounds were confirmed by ¹H NMR and elementary analysis. These compounds were screened for herbicidal activity against rape and barnyard grass. Compound B13 exhibited moderate herbicidal activity.     

(E)‐2‐(2‐Adamantylidene)‐3‐(1‐ferrocenylethylidene)succinic anhydride

The title compound, [Fe(C₅H₅)(C₂₁H₂₁O₃)], was obtained from successive Stobbe condensations between ketones and di­methyl succinate. The succinic anhydride five‐membered ring is distorted significantly from planarity, with the buta­diene moiety being twisted by 49.3 (2)° from planarity and the C atoms at the succinic anhydride end of the alkene bonds showing significant pyramidalization. The cyclo­penta­diene rings of the ferrocenyl moiety adopt an almost eclipsed conformation.     

The Synthesis of 2‐(Chromon‐2/3‐yl)‐3‐(5‐thione‐4‐hydro‐1,3,4‐thiadiazol‐2‐yl)‐4‐oxo‐thiazolidine

2‐Formylchromones and 3‐formylchromones as the first materials singly reacted with 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole to give the corresponding Schiff bases, which on cyclocondensation with mercapto‐acetic acid in 1,4‐dioxane yielded target compounds named 4‐oxo‐thiazolidines. The structures of all the synthetic compounds were confirmed by elemental analysis and IR, ¹H NMR, LC‐MS (ESI) spectral data.     

(E)‐6‐Methoxy‐3‐(α‐methoxybenzyl­idene)benzo[b]furan‐2(3H)‐one at 173 K

The title compound, C₁₇H₁₄O₄, is an unprecedented new synthetic isoaurone‐type enol ether that has the E configuration. The planar furanone ring is fused to a methoxy­benzene ring system, with an interplanar angle of 175.7 (1)°. Due to this ring fusion, the six‐membered ring has a significant amount of ring strain, as shown by the internal ring angle range of 115.8 (1)–124.7 (1)°, whereas the vinylic phenyl ring has internal angles between 119.7 (1) and 120.2 (1)°. The mol­ecules form infinite hydrogen‐bonding layers along the b direction of the form C—H?O, where the keto O atom acts as a bifurcated acceptor. These layers are connected along the c direction by another hydrogen bond with a methoxy H atom as donor. In addition to this connection, the layers are stacked via centres of symmetry by a pair of symmetry‐related benzo­furan­one ring systems.     

3β‐(1‐Allyl‐1‐pyrrolidinio)‐16‐(2‐pyridylmethylene)androst‐5‐en‐17β‐ol bromide hemihydrate

The title compound, C₃₂H₄₅N₂O⁺·Br^?·0.5H₂O, has the outer two six‐membered rings in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐mem­bered ring of the steroid nucleus adopts a slightly deformed 14α‐envelope conformation. The pyridyl­methyl­ene moiety has an E configuration with respect to the hydroxyl group at position 17. The structure is stabilized by a network of O—H?Br‐type intermolecular hydrogen bonds.