An efficient hydrocyanation of α, β-unsaturated diesters with TMSCN catalyzed by MgI2 etherate

Abstract

A mild, efficient and highly regioselective addition of trimethylsilyl cyanide (TMSCN) to α,β-unsaturated diesters has been achieved by using MgI₂ etherate as catalyst under solvent-free conditions. This protocol provides the corresponding β-cyano esters in high yields.     

Selectivity of hydrogenations. Part 4 6- and 8-substituted quinaldines yield of tetrahydroderivatives and basicities of quinolines

Hydrogenation of 6- or 8-R-substituted quinaldines [R=H, CH₃, CH(CH₃)₂, C(CH₃)₃, or CF₃] over platinum in trifluoroacetic acid gave higher yields (90%) of 5,6,7,8-tetrahydroderivatives than hydrogenation of the corresponding quinolines. ThepKa-values of 20 quinolines and quinaldines were determined by measuring the half-neutralization potentials in acetic anhydride. More basic quinolines gave higher yields of 5,6,7,8-tetrahydroproduct; exceptions are 6- and 8-methylquinoline and 8-tert. butylquinoline. Explanations for these observations are suggested.Dedicated to Prof. Dr.K. Schlögl on the occasion of his 60th birthday.     

Reactions of Various Nucleophiles with d-Glucal over Keggin-Type Heteropoly Compounds: A Simple,Rapid, and Expedient Method for the Synthesis of Pseudoglycals

The reaction of benzyl alcohol with 3,4,6-tri-O-acetyl-d-glucal has been investigated with several heteropoly compounds, and the optimal catalyst is 12-tungstophosphoric acid supported on carbon. In the presence of this catalyst, various alcohols gave the corresponding alkyl and aryl 2,3-unsaturated glycopyranosides in excellent yields and good anomeric selectivity under solvent-free condition. 4,6-Di-O-acetyl-2,3-dideoxy-α-d-erythro-hex-2-enopyranosyl cyanide and ethyl 4,6-di-O-acetyl-2,3-dideoxy-1-thio-α-d-erythro-hex-2-enopyranoside have also been prepared with trimethylsilyl cyanide and ethanthiol as nucleophiles, respectively. The catalyst could be easily recovered and reused several times with slight loss of activity. The selectivity to give α-anomers predominantly did not show any change in all runs.     

Synthesis of 1-phenyl-6H-anthra[1,9-b,c]furan-6-one (furanoanthrone) derivatives by the reaction of 1-acyloxy-9,10-anthraquinones with benzyl cyanide

The reactions of various I-acyloxyanthraquinones with benzyl cyanide in DMSO in the presence of K₂CO₃ were studied. 1-Phenyl-6H-anthra[1,9-b,c]furan-6-one derivatives are formed as the main reaction products. In the case of unsubstituted I-acyloxyanthraquinones, 1-phenyl-6H-anthra[1,9-b,c[furan-6-one and I-phenylanthra[1,9-b,clpyran-2,l-dione were isolated. It was shown that furanoanthrones can be synthesized in two steps via the corresponding pyronoanthrones.Translated fromlzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2714–2714, November, 1996.     

Inductivity and Bridging in 2-Bicyclo[2.2.2]octyl Cations. Polar Effects,Part 11

The solvolysis rates and products of several 6-substituted 2-exo- and 2-endo-Bicyclo[2.2.2]octyl p-toluenesulfonates, 12 and 13 , respectively, are reported. Inductivity, as measured by the reaction constants ρ_I, is considerably less in the exo-series 12 (ρ_I = ?1.50) than in the corresponding 2-exo-norbornyl p-toluenesulfonates 1 (ρ_I= ?2.0). It is proposed that, for geometrical reasons, bridging of the cationic center C(2) by C(6) is not as strong in the bicyclooctane series 12 as it is in the norbornane series 1 . On the other hand, inductivity is higher in the 2-endo-bicyclooctane series 13 (ρ_I= ?1.0) than in the corresponding 2-endo-norbornane series 3 (ρ_I = 0.78), probably, because in the former case bridging of C(6) is less hindered by the departing anion. The relative yields of exo- and endo-substitution products from the series 12 and 13 , are in accord with graded bridging of C(6) in the incipient bicyclooctyl cations. But almost constant bridging of C(2) by C(7) is indicated in the ionization of the 2-endo-bicyclooctane series 13 . Consequently, in the free unsubstituted bicyclooctane cation C(2) is bridged symmetrically by C(6) and C(7), in contrast to the current concept of ‘non-classical’ two-electron-three-center bonding.     

SN2 Reactions with Carboxylic Esters. Selective cleavage of methyl esters

Sodium cyanide in hexamethylphosphoric triamide selectively cleaves methyl esters in the presence of ethyl esters with yields of ca. 80%. The mechanism of the reaction has been investigated. It consists of nucleophilic displacement by cyanide of the carboxylate ion from the alcohol carbon atom (B_Al2 mechanism).     

无溶剂一锅法Al(ClO4)3催化合成α-氨基膦酸酯

以无水高氯酸铝为催化剂, 将芳香醛、芳香胺及亚磷酸酯在无溶剂条件下一锅法反应, 高效地合成了α-氨基膦酸酯, 该催化剂优于其它已发现的催化剂[如Mg(ClO₄)₂, BiCl₃, AlCl₃等], 建立了一种适用于含有钝化基团的芳香胺的α-氨基膦酸酯的新合成方法.     

Practical and General Method for Direct Synthesis of Alkyl Fluorides from Alcohols under Mild Conditions

A variety of alcohols were treated with Ph₃P and KF in CCl₄-DMF at room temperature to afford the corresponding fluorides in very good yields.     

Displacement of Activated Amino Groups. C,N- vs. N,S-Bond Cleavage in the Reaction of N-Alkyl-disulfonamides with Nucleophiles

Sodiumthiophenoxide and sodiumphenylselenide react with N-benzyl- and N-hexyl-di-p-toluenesulfonamides ( 1 and 2 ) via displacement at the C-atom to afford the corresponding organosulfides and selenides in yields of 68–96%. In contrast, sodium cyanide converts disulfonamides to monosulfonamides by attack on the S-atom. The different selectivities of phenylsulfide and selenide as compared to cyanide anions with respect to attack on the C- and S-atoms are rationalized on the grounds of the HSAB (hard and soft acids and bases) principle of Pearson.     

Practical and General Method for Direct Synthesis of Alkyl Fluorides from Alcohols under Mild Conditions

Summary. A variety of alcohols were treated with Ph₃P and KF in CCl₄-DMF at room temperature to afford the corresponding fluorides in very good yields.     

Synthese nouvelle d'alcynes α-silicies

In the presence of catalytic amounts of copper(I) chloride, and at 150° in an autoclave methylchlorosilanes Me₄ SiCl_4-n (n = 1,2,3) react with terminal alkynes RCCH (R = n-Bu, Ph) leading to the corresponding alkynylmethyl-chlorosilanes, RCCSiMe₄ Cl_3-n, in good yields.     

Pyridazines. LXXXIV. Studies on borohydride reduction of pyridazine compounds

Imidazo[1,2-b]pyridazine, s-triazolo[4,3-b]pyridazine and tetrazolo[1,5-b]pyridazine and some derivatives thereof were reduced with sodium borohydride to give the corresponding 5,6,7,8-tetrahydro derivatives. A mechanism for these reductions is proposed and reduction at the C₇-C₈ bond occurs before the reduction of the C₆? N₅ bond. Substituents at position 7 and/or 8 cause a significant decrease in the extent of reduction or lead to a 5,6-dihydro derivative by competitive attack at the 6 position.     

Furopyridines. XXIX. Reactions of furo[2,3-b:4,5-c‘]-, -[3,2-b:-4,5-c’]-, -[2,3-c:4,5-c‘]- and -[3,2-c:3,2-c’]dipyridine

Furo[2,3-b:4,5-c‘]- 1a , -[3,2-b:4,5-c’]- 1b , -[2,3-c:4,5-c‘]- 1c and -[3,2-c:4,5-c’]dipyridine 1d were derived to the N-oxides 2a-d , N‘-oxides 2′b , 2′c or N,N’-dioxide 3b-d by N-oxidation with m-chloroperbenzoic acid. Chlorination of these N-oxides, N′-oxide and N,N′-dioxides with phosphorus oxychloride afforded compounds chlorinated at the α-position(s) to the ring nitrogen 4a-d , 4′c , 14b-d and 14′b . Acetoxylation of N-oxides 2a-d and 2′c with acetic anhydride gave the corresponding pyridone compounds 6a-d and 6′c in good yields, while the acetoxylation of N,N′-dioxides gave a complex mixture from which no compound could be isolated. Cyanation of 2a-d, 2′c and 3b-d with trimethylsilyl cyanide yielded the cyano compounds 7a-d , 7′c , cyano-N-oxides 15b-d and dicyano compounds 15′c and 15′d . Monocyano compounds 7a-d and 7′c were converted to the imino esters 8a-d and 8′c by treatment with sodium ethoxide. Imino esters were derived to the carboxylic esters 9a-d and 9′c , from which the corresponding alde hydes 10a-d and 10′c were obtained by reduction with diisobutylaluminum hydride. Dicyanide 15′c was converted to dialdehyde 19 by the treatment with sodium ethoxide, and the subsequent hydrolysis of the imino ester and reduction of the carboxylic ester with diisobutylaluminum hydride.     

Polarized ethylene. V. Synthesis of 1-substituted indolizine,pyrazolo[1,5-a]pyridine,and their related compounds using methoxyethylene derivatives

The reaction of pyridinium or isoquinolinium N-ylides with methoxy-substituted ethylenes gave the corresponding indolizine and pyrrolo[2,1-a]isoquinoline derivatives bearing acetyl, aroyl, cyano, ester group at the 1-position in one step. Pyrazolo[1,5-a]pyridine, pyrazolo[1,5-a]quinoline, and pyrazolo[5,1-a]isoquinolines were also synthesized in good yields from the corresponding aromatic N-imines and methoxyethylene derivatives.     

Reaction of ketenes with N,N-disubstituted α-aminomethyleneketones. XVIII. Synthesis of N,N-disubstituted 4-amino-3-phenyl-2H-naphtho[1,2-b]pyran-2-ones

1,4-Cycloaddition of phenylchloroketene to N,N-disubstituted 2-aminomethylene-3,4-dihydro-1(2H)naphthalenones gave the corresponding adducts, namely N,N-disubstituted 4-amino-3-chloro-3,4,5,6-tetrahydro-3-phenyl-2H-naphtho[1,2-b]pyran-2-ones II, in the case of aliphatic N,N-disubstitution or aromatic N-monosubstitution. Apart from IIf (NR₂ = NMePh), adducts II were unstable and were dehydrochlorinated in situ with DBN to give N,N-disubstituted 4-amino-5,6-dihydro-3-phenyl-2H-naphtho[1,2-b]pyran-2-ones III in fair overall yields. Compounds III were dehydrogenated with Pd/C in boiling p-cymene to afford the title compounds generally in high yields.     

Preparation of certain 2-N-alkylamino-and 2-N,N-dialkylamino-10-methylphenothiazines via phenothiazyne

The treatment of 2-chloro-10-methylphenothiazine, 1 , with lithium alkylamide/alkylamine or lithium dialkylamide/dialkylamine yields the corresponding 2-N-alkylamino-or 2-N,N-dialkylaminophenothiazines in good yields via phenothiazyne. No significant reduction of 1 to 10-methylphenothiazine is observed. Yields of amines obtained by this method are considerably higher than those obtained by reacting 1 with sodamide in refluxing amine solvent. Attempts to introduce the -CH₂CN moiety onto the phenothiazine nucleus by treating 1 with sodamide and acetonitrile in liquid ammonia produced only 2-amino-10-methylphenothiazine.     

Synthesis of nitrogen-containing heterocycles. 5. A new route to 5-amino-[1,2,4]triazolo[1,5-a][1,3,5]triazine derivatives

Treatment of certain diaminomethylenehydrazones 1 of aromatic carbonyl compounds with ethyl N-cyanoimidate ( 2 ) in acetonitrile in the presence of a tertiary amine at room temperature gives the corresponding amino(N-cyanoiminomethyl)aminomethylenehydrazones 3 in high yields. The intermediate 3 can readily be cyclized to the corresponding 5-amino-2,3-dihydro[1,2,4]triazolo[1,5-a][1,3,5]triazines 4 in moderate to good yields by brief heating in acetonitrile. When the reaction of diaminomethylenehydrazones 1 with ethyl N-cyanoimidate ( 2 ) is performed at reflux temperature in the presence of a tertiary amine, 5-amino-2,3-dihydro[1,2,4]triazolo[1,5-a]1,3,5]triazines 4 can be directly obtained in moderate yields. The yields of triazolotriazine produced by the one-step synthesis are generally comparable or even higher than the overall yields from the two-step procedure.     

Pyrimidines,Part XXXI . Synthesis,reactions and properties of 6-acyl-1,3-dimethylpyrrolo[2,3-d]pyrimidine-2,4-diones

Acylations of 1,3-dimethyl- ( 1 ) and 1,3,7-trimethylpyrrolo[2,3-d]pyrimidine-2,4-dione ( 2 ) with anhydrides in the presence of trifluoroacetic acid proceed well to give in good yields the corresponding 7-acyl derivatives 3–11 . The 6-trichloroacetyl derivatives 5 and 6 are sensitive towards nucleophiles, which displace the trichloromethyl group easily by formation of the corresponding 6-carboxylic acid derivatives 12–23. The newly synthesized compounds have been characterized by elemental analysis, uv and ¹H nmr spectra and pK_a, determinations.     

Ring closure reactions with nitriles. II. Formation of pyrrolo[1,2-a] quinazolines and thiazolo[3,2-a] quinazolines

2-Quinazolinepropionic acids have been obtained from the reactions of potassium cyanide with o-carboxy- or o-acyl-3-chloropropionanilides. Some of these compounds have been cyclized to pyrrolo [1,2-a] quinazolines. The reaction of an o-carbethoxy-2-chloroacetanilide with potassium thiocyanate formed a 2-quinazolinylthioacetic acid, which was cyclized to a thiazolo-[3,2-a]quinazoline. A mechanism is presented for the formation of these compounds.     

Mechanochemical Strecker Reaction: Access to α‐Aminonitriles and Tetrahydroisoquinolines under Ball‐Milling Conditions

A mechanochemical version of the Strecker reaction for the synthesis of α‐aminonitriles was developed. The milling of aldehydes, amines, and potassium cyanide in the presence of SiO₂ gave the corresponding α‐aminonitriles in good to high yields. The high efficiency of the mechanochemical Strecker‐type multicomponent reaction allowed the one‐pot synthesis of tetrahydroisoquinolines after a subsequent internal N‐alkylation reaction.