6,11-Dioxa-D-homoanalogs of steroids by reaction of 2-acetyl-2-cyclohexen-1-ones with 4-hydroxycoumarins

Unsubstituted 2-acetyl-2-cyclohexetz-1-one reacts with 4-hydroxycoumarin following the pattern of a Diels -Alder heterodiene condensation to form 12-methyl-6,11-dioxa-9-hydroxy-D-homo-1,3,5(10), 12-tetraene-7,17a-dione. In the case of 2-acetyl-5,5-dimethyl-2-cyclohexen-1-one, reaction with both 4-hydroxy- and 4,7-dihydroxycoumarin follows the pattern of a Michael addition with the formation of 3-(2-acetyl-5,5-dimethyl-3-oxocyclohexyl)-4-hydroxy-and 4,7-dihydroxy coumarin respectively. Dehydration of both types of adduct gives 6,11-dioxa-D-homoanalogs of steroids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 345–348, March, 1994.     

Asymmetric Morita-Baylis-Hillman reactions of 2-cyclohexen-1-one catalyzed by chiral biaryl-based bis(thiourea) organocatalysts

Newly-developed bis(thiourea) 1d was found to be an efficient organocatalyst for the Morita-Baylis-Hillman reaction. High enantioselectivities were obtained in the reaction of 2-cyclohexen-1-one with both aromatic aldehydes (up to 84% ee) and aliphatic aldehydes (up to 96% ee).     

Synthesis of polyfunctionalized furans from 3-acetyl-1-aryl-2-pentene-1,4-diones

The BF₃-catalyzed cyclization of 3-acetyl-1-aryl-2-pentene-1,4-diones 1a-e in the presence of water in boiling tetrahydrofuran gave bis(3-acetyl-5-aryl-2-furyl)methanes 2a-e in 26-79% yields along with a small amount of 3-acetyl-5-aryl-2-methylfurans 3a-e. The exact structure of 2a was determined by X-ray crystallography. The use of a half volume of the solvent for the reaction of 1a resulted in the formation of 2,4-bis(3-acetyl-5-phenyl-2-furfuryl)-3-acetyl-5-phenylfuran (4) together with 2a and 3a. A similar reaction of 1a was carried out in the presence of 3-acetyl-5-(4-methylphenyl)-2-methylfuran (3d) to afford 4-(3-acetyl-5-phenyl-2-furfuryl)-3-acetyl-5-(4-methylphenyl)-2-methylfuran (5) in 49% yield. The BF₃-catalyzed reaction of 1a with 2,4-pentanedione in dry tetrahydrofuran at 23°C gave 3-(3-acetyl-5-phenyl-2-furfuryl)-4-hydroxy-3-penten-2-one (6a) and 3-(3-acetyl-2-methyl-4-phenyl-5-furyl)-4-hydroxy-3-penten-2-one (7a) in 66 and 24% yields, respectively. The product distribution depended on the reaction temperature. A similar reaction of 1b-e also yielded the corresponding trisubstituted furans 6b-e and tetrasubstituted furans 7b-e in good yields. These results suggested the presence of the furfuryl carbocation intermediate A during the reaction. The one-pot synthesis of 6a and 7a was also achieved by a similar reaction using phenylglyoxal. The deoxygenation of 1a with triphenylphosphine gave 3a in 88% yield, while 1a was treated with concentrated hydrochloric acid to yield 3-acetyl-2-chloromethyl-5-phenylfuran (8) which was quantitatively transformed in ethanol into 3-acetyl-2-ethoxymethyl-5-phenylfuran (9) and in water into 3-acetyl-5-phenylfurfuryl alcohol (10), respectively. In addition, the Diels-Alder reaction of cyclopantadiene with 1a gave the corresponding [4+2] cycloaddition products 11 and 12.     

A Convenient Method for the Preparation of Linear Furoquinolin-2-ones

Fries rearrangement of 7-acetoxy-4-methylquinolin-2-one and subsequent condensation of the 6-acetyl-7-hydroxy-4-methylquinolin-2-one obtained with -chloro ketones gives a series of furo[3,2-g]quinolin-7-ones.     

Condensation Op 3-Acetyl-and 3-Acetyl-4-Methyl-2H-1-Benzopyran-2-One with Aromatic Adehydes

The reactivities of 3-acetyl-2H-1-benzo-pyran-2-one (2) and 3-acetyl-4-methyl-2H-1-benzopy-ran-2-one (3)are compared in the condensation with aromatic aldehydes. It is established that the benzopyrones 2 and 4 condense with various aromatic aldehydes in chloroform containing some drops of piperidine by boiling for 7 hours and azeotropic distillation of water, yielding 3-cinnamoyl-2H-1-benzopyran-2-ones (3a-g) and 4-(2-arylvinyl)-3-acetyl-2H-1-benzopyran-2-ones (6a-f), respectively. Evidence is provided that benzopyrone 4 participates in the condensation with the methyl group in position 4. A probable mechanism of the process is proposed.     

5-Methyl-2-furylglyoxal, 5-Methyl-4-nitro-2-furylglyoxal, and Their Derivatives. Nitration of 2-(5-Methyl-2-furyl)quinoxaline

The oxidation of 2-acetyl-5-methyl-4-R-furans (R = H, NO₂) by selenious acid was studied. Derivatives substituted at the C=O groups of the corresponding glyoxals were obtained. The nitration of 2-(5-methyl-2-furyl)quinoxaline was carried out at C_(4'). Oxidative splitting of the -nitrofuryl group occurs at the C₍₄₎-C₍₅₎ and C₍₅₎-O bonds.     

Syntheses based on 2 -prenyldi hydroresorcinol

Summary On the basis of dihydroresorcinol we prepared 2,2-dimethylchroman-5-ol, 2-prenyl-3-methyl-²-cyclohexen-1-one, 6-methyl-1-tetralone, geranylacetic acid, and 8-rnethyl-⁸-decenoic acid.     

Allylic oxidation of cyclohexene over silica immobilized iron tetrasulfophthalocyanine

Iron tetrasulfophthalocyanine was immobilized on silica (FePcS-SiO₂) and its activity examined on the allylic oxidation of cyclohexene using TBHP as oxidant. Under our reaction conditions, attack of the activated C-H bond was preferred instead of the epoxidation of CC bond, yielding 2-cyclohexen-1-one as the main product. μ-Oxo dimeric (d-FePcS) appears to be the active species for this reaction.     

Copper-catalyzed asymmetric addition of Et2Zn to 2-cyclohexen-1-one and 2-carbamoyloxy-2-cyclohexen-1-one with phosphoramidite,phosphite, and bidentate phosphite–oxazoline ligands

New biphenol-backboned phosphite–oxazoline bidentate ligands were synthesized and applied in the copper-catalyzed asymmetric conjugate additions on 2-cyclohexen-1-one with Et₂Zn. In these reactions, the non-chiral oxazoline unit has demonstrated significant impact on the enantioselectivity. 2-Carbamoyloxy-2-cyclohexen-1-one is a new α-oxygenated cyclic enone substrate and was synthesized and applied to the aforementioned addition with certain phosphoramidite, phosphite, and the new bidentate ligands. Good ee has been obtained on this substrate.     

Synthesis of phenyl-substituted derivatives of decahydrophenanthridine-1, 7-dione and hexahydro-8-isoquinolone

2-Bromo-2-aroylcydohexan-1-ones were prepared by bromination of 2-aroylcyclohexan-1-ones with Nbromosucccinimide and were isomerized into 6-bromo-2-aroylcyclohexan-1-ones in attempted dehydrobromination by heating in organic solvents. The reaction of 2-benzoyldimedone with oxalyl chloride was investigated. The 2-benzoyl-3-chloro-5,5-dimethyl-2-cyclohexen-1-one obtained formed 2-benzoyl-5,5-dimethyl-2-cyclohexen-1-one in reduction with zinc activated with silver acetate. The cyclohexenone was reacted with some enaminocarbonyl compounds, yielding derivatives of decahydrophenanthridine-1,7-dione and hexahydro-8-isoquinolone.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 631–635, May, 1992.     

Catalytic,asymmetric aza-Baylis–Hillman reaction of N-sulfonated imines with 2-cyclohexen-1-one and 2-cyclopenten-1-one in the presence of a chiral phosphine Lewis base

In the aza-Baylis–Hillman reaction of N-sulfonated imines with 2-cyclohexen-1-one or 2-cyclopenten-1-one, we found that by using (R)-2′-dimethylphosphanyl-[1,1′]binaphthalenyl-2-ol LB1 as a chiral phosphine Lewis base, the corresponding Baylis–Hillman adducts 2 or 3 can be obtained in good yields and moderate enantiomeric excess. The structure of this chiral phosphine Lewis base on chiral induction in this reaction has also been discussed.     

Asymmetric Morita-Baylis-Hillman reaction of arylaldehydes with 2-cyclohexen-1-one catalyzed by chiral bis(thio)urea and DABCO

Novel bis(thio)urea organocatalysts were synthesized from axially chiral (R)-(-)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl-2,2'-diamine (H8-BINAM), and their catalytic abilities have been examined in the Morita-Baylis-Hillman reaction of 2-cyclohexen-1-one or 2-cyclopenten-1-one with a wide range of aromatic aldehydes in combination with DABCO. The best result was achieved in the reaction of 3-fluorobenzaldehyde with 2-cyclohexen-1-one to give the desired Morita-Baylis-Hillman product in 79% yield and 88% ee.     

An alternative approach to para-C-H arylation of phenol: palladium-catalyzed tandem γ-arylation/aromatization of 2-cyclohexen-1-one derivatives

An efficient approach to prepare para-aryl phenols has been developed by using a Pd-catalyzed tandem γ-arylation/aromatization of 2-cyclohexen-1-one derivatives with aryl bromides. This approach provides various p-aryl phenols from the phenol surrogates, 2-cyclohexen-1-one derivatives, in a single reaction step on the basis of C-H arylation.     

Reaction of 2-substituted 5,5-dimethyl-4-oxo-1-pyrroline-1-oxides with nucleophilic reagents and synthesis of nitroxyl radicals—derivatives of pyrrolidine

The reaction of -oxonitrones, derivatives of pyrroline, with nitrogeneous nucleophiles and NaBH₄ proceeds at the carbonyl group with the retention of the nitrone group. The reaction with organomagnesium and organolithium compounds takes place at the nitrone group with the retention of the carbonyl group, while the oxidation of the products formed proceeds to form nitroxyl radicals—Derivatives of pyrrolidin-4-one, which were used in the synthesis of spin-labeled dioximes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 390–395, February, 1990.     

Efficient stepwise and one pot three-component synthesis of 2-amino-4-(2-oxo-2H-chromen-3-yl)thiophene-3-carbonitriles

Environmentally benign conditions have been developed for the synthesis of 2-amino-4-(2-oxo-2H-chromen-3-yl)thiophene-3-carbonitriles (3) starting from 3-acetyl-2H-chromen-2-one (1) through the intermediacy of 2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)malononitrile (2) using the Knoevenagel condensation followed by the Gewald reaction. Alternatively, 3 could also be prepared in a one pot method by treating equimolar amounts of 1, malononitrile, and elemental sulfur. The merits of this preparation are mild reaction conditions, easy work-up procedure, and good yields.     

Introduction of substituents in the pyridine proton of 7-azaindoline

Electropilic substitution (nitration, bromination, and chlorination) of 4-methyl-6-chloro-7-azaindoline (and its N-acetyl derivative) takes place in the 5 position. 4-Methyl-5-amino-7-azaindoline, 4-methyl-5-nitro-7-azaindoline, and 1-acetyl-4-methyl-5-amino-6-chloro-7-azaindoline were obtained by reduction of 1-acetyl-4-methyl-5-nitro-6-chloro-7-azaindoline under various conditions. A method was developed for the preparation of a new three-ring system — 1,2,3-oxadiazolo[5,4-b]-pyrrolo[2,3-e]pyridine.Communication L from the series Derivatives of Azaindoles. See [1] for communication XLIX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 380–384, March, 1977.     

Reactions of phenylthiotrimethylsilylmethyllithium: Preparation of α-phenylthioketones and additions to 2-cyclohexen-1-one

Phenylthiotrimethylsilylmethyllithium(1) was reacted with a variety of electrophiles, including some containing two functional groups. α-Phenylthiolketones were obtained from the reaction with esters. The anion(1) underwent either 1,2- or 1,4-addition, depending on the conditions used, with 2-cyclohexen-1-one.     

A new possibility of construction of the CD ring systems of the steroid molecule

Summary We have carried out the cyclization of 2-(-cyclohexylidene ethyl)-2-cyclohexen-1-one (I) into trans-1-keto-^4a,10a-dodecahydrophenanthrene (II) under the influence of phosphoric acid.     

Synthesis of functional derivatives of trifluoromethylpyrimidines from acetylacetone,trifluoroacetonitrile, and aryl isocyanates

1, 1,1-Trifluoro-2-amino-3-acetyl-2-penten-4-one was obtained by the addition of acetylacetone to trifluoroacetonitrile in the presence of catalytic amounts of nickel acetylacetonate. The reaction of 1,1,1-trifluoro-2-amino-3-acetyl-2-penten-4-one with aryl isocyanates gave 1-aryl-5-acetyl-6-methyl-4-trifluoromethyl-1H-pyrimidin-2-ones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2639–2642, November, 1991.     

Chiral phosphorus ligands for the asymmetric conjugate addition of organocopper reagents

The asymmetric conjugate addition of medium order alkyl cuprate reagents. R₅Cu₃Li₂, to 2-cyclohexen-1-one. 2-cyclopenten-1-one and 2-cyctohepten-1-one, with the help of phosphorus ligand B^*, is described. 3-Alkyl substituted cyclohexanones are obtained in essentially optically pure form. The same chiral ligand, associated with CuI, in catalylic amount (10%), allows the asymmetric conjugate addition of Et₂Zn to 2-cyclohexen-1-one.