Reaction of 4,5-diamino-1,6-dihydropyrimidin-6-ones with two equivalents of chalcones

The reaction of 4,5-diamino-1,6-dihydropyrimidin-6-ones 1 with two equivalents of the chalcones 2 leads in an acidic medium to the formation of the 2,3,6,7-tetrahydro-1H-pyrimido[4,5-b][1,4]diazepin-6-one derivatives 3a-d . The structure elucidation of the products is based on nmr measurements and an X-ray diffraction.     

The clemmensen reduction of α,β-unsaturated ketones

The deoxygenation of the α,β-unsaturated ketones (1) and (5) under the Clemmensen condition yielded the olefins (2) and (6) along with their respective dimers (3+4) and (8+9). The α , β-unsaturated ketone (13) under similar treatment yielded the olefin (14) in satisfactory yield but the dimer could not be characterized. The deoxygenation of the α,β-unsaturated ketones (10) and (16) under similar con- ditions afforded the olefins (12) and (15) respectively in satisfactory yield along with the rearranged olefins (11) and (17) respectively. Epox-idation of the olefin (17) followed by heating with p-toluenesulfonic acid yielded the ketone (18).     

Reactions of α,β-unsaturated ketones with cyanoacetamide

3-Aryl-1-phenyl-2-propen-1-ones Ia-f and aroylphenylacetylenes Va-d reacted under reflux for 3 hours with cyanoacetamide in the presence of sodium ethoxide to give the corresponding 4-aryl-3-cyano-6-phenyl-2-(1H)pyridones VI. However, when ketones Ia-e were refluxed with cyanoacetamide for one hour in the presence of sodium ethoxide or piperidine, they gave the corresponding 4-aryl-3-cyano-3,4-dihydro-6-phenyl-2-(1H)pyridones IIIa-e, which upon heating with selenium gave the corresponding 2-pyridones VI. The structures of the products are based on chemical and spectroscopic evidence.     

The high resolution mass spectra of α,β-unsaturated and α-chloromercuri-α,β-unsaturated steroidal ketones

The high resolution mass spectra (500 eV) of some α,β-unsaturated steroidal ketones have been studied and compared with the spectra of the corresponding α-chloromercuri ketones. In the latter, the carbon-mercury bond frequently remains intact at the expense of the fission of two carbon-carbon bonds. The abundance of mercury-containing ions allows the use of the mercury atom fingerprint in confirming ring B fragmentation of the steroid nucleus at C(6)–C(7) and C(9)–C(10) for 5α-androst-1-ene-3,17-dione, 1,4-androstadiene-3,17-dione and their 2-chloromercuri derivatives; and at C(7)–C(8) and C(9)–C(10) for 1,4,6-androstatriene-3,17-dione, 1,4,6-androstarien-17 β-ol-3-one and their 2-chloromercuri derivatives. 2-Chloromercuri-1,4,6-androstatriene-3,17-dione and 2-chloromercuri-1,4,6-androstatrien-17 β-ol-3-one also give an abundant ion as the result of ring C fragmentation at C(8)–C(14) and C(11)–C(12), the chloromercuri group being replaced by a hydrogen atom. This ring C cleavage gives the only recognizable distinctive fragmentation ion for 1,4,6-pregnatriene-3,20-dione and 2-chloromercuri-1,4,6-pregnatriene-3,20-dione. For most of the mercurated steroids, the low resolution mass spectra (70 eV) are reported. In these spectra, the fragmentation patterns are similar to those obtained using the higher ionization energy employed for the high resolution spectra.     

Palladium-catalyzed conjugate addition type reaction of 5-iodopyrimidines with α,β-unsaturated ketones

The reaction of various 5-iodopyrimidines with α,β-unsaturated ketones in the presence of palladium diacetate-triphenylphosphine complex in triethylamine are investigated. In the reaction of 2,4-dialkoxy(or alkylthio)-6-methyl-5-iodopyrimidine the addition of pyrimidine to the carbon? carbon double bond of α,β-unsaturated ketones occurs. In the case of other pyrimidines, according to the decrease of steric hindrance at the 5-position on the pyrimidine ring, the ratio of conjugate addition product was decreased and the usual olefinic substituted product was increased.     

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.     

1,4-Conjugate addition of allyltrimethylsilane to α,β-unsaturated ketones

α,β-Unsaturated ketones smoothly undergo conjugate addition with allyltrimethylsilane in the presence of a catalytic amount of elemental iodine under very mild and convenient conditions to afford the corresponding Michael adducts in high yields with high selectivity.     

Reactions of β-sulfenyl α,β-unsaturated ketones with guanidine,Amidines, and diamines

β-Sulfenyl α, β-unsaturated ketones 1a-c reacted with guanidine or amidines to give pyrimidine derivatives 3 in 14-76% yields. Treatment of ketones 1 with diamines such as ethylenediamine and o -phenylenediamine afforded the seven-membered heterocycles, 2,3-dihydro-1,4-diazepine 5 and 2,3-benzo-1,4-diazepines 8a-c .     

Synthesis of α,β-unsaturated oxathiolanes

The formation of α,β-unsaturated oxathiolanes 2 from α,β-unsaturated carbonyl derivatives was achieved selectively and in high yields using the heterogeneous catalyst APSG·HCl.     

Mass spectra of some acyclic α,β-unsaturated aldehydes,ketones and esters

The mass spectra of a series of aliphatic acyclic α,β-unsturated aldehydes, ketones and ester have been examined. The spectra do not show evidence for McLafferty rearrangements, alkoxyl migration or for fragmentations which are dependent upon the s-trans or s-cis conformations of the compounds. There is some evidence for cis-trans isomerism about the double bond.     

Condensation of 3-methylbenzoxazolinone with α,β-unsaturated acids

The reaction between 3-methylbenzoxazolinone and some unsaturated acids in PPA leads to mixtures of compounds, depending on the acid: 6-crotonyl- (or cinnamoyl)-3-methylbenzoxazolinones, 2,3-dihydro-2,5-(or 2,7)dioxo-3-methylcyclopenta[f]benzoxazoles and 6-(3-oxo-indanyl)-3-methylbenzoxazolinones. The structure of the products was established by ¹³C and ¹H nmr spectroscopy and (or) by independent synthesis. Possible mechanisms of the reaction are discussed; when competition is possible as in the last step of the cyclization, the benzene ring shows a higher reactivity than the aromatic nucleus of the benzoxazolinone; the contrary is observed when the benzene ring is p-chloro-substituted.     

Reaction of Cα,O-dilithiooximes with functionalized carbonyl compounds. Part 2 . Reaction with α-chloroketones and α,β-unsaturated aldehydes and ketones

The reaction of Cα,O-Dilithiooximes 2 and α-chloroketones afforded 5-(hydroxymethyl)-Δ²-soxazolines 4 . α,β-Unsaturated aldehydes and ketones reacted with 2 to give the corresponding acyclic 1,2-addition products 5 . The latter were cyclized with phosphorus pentoxide to 5-vinyl-Δ²-isoxazolines 6 .     

Reaction of singlet oxygen with α,β-unsaturated aldimines

The reaction of singlet oxygen with N-1-(2-alkenylidene)-t- butylamines ( and ) gives the unsaturated hemiperacetal derivatives ( and 4) of the hydroperoxy aldimines ( and ). Several α, β-unsaturated aldimines which are held in the s-trans conformation failed to react with singlet oxygen.     

The reaction of active and stabilized phosphonium ylides with α,β-unsaturated carbonyl compounds [1]

The active ketenylidene-(2a) or thioketenylidenetriphenylphosphoranes (2b) react with 2-benzylidene-1,3-indandione (1), 5-benzylidenebarbituric acid (11), and 4-benzylidene-1,2-diphenyl-3,5-pyrazolidinedione (16) to give the corresponding pyranones and thioxopyranones (3a,b, 12a,b) and (17a,b), respectively. On the other hand, compounds 1 and 11 can be converted by reaction with the stabilized alkylidenephosphoranes 4a–e into the phosphoranylidenes 6a–e and 13a–e. Moreover, the oxaphosphinins 8 or 14 and the oxazaphosphinins 10 or 15 were obtained when compounds 1 and 11 were allowed to react with the phosphorane 7 and the iminophosphorane 9, respectively. Some of these new organophosphorus compounds are found to have insecticidal and molluscicidal properties against cotton leafworm Spodoptera littoralis larvae and Biomphalaria alexandrina snails. © 1997 John Wiley, & Sons, Inc.     

Captodative α,β-unsaturated oxazolines as dienophiles in the asymmetric Diels-Alder reaction

Captodative oxazoline derivative 5a gave rise to four-cycloadducts 6, 7, 8 and 9 in the presence of trifluoroacetic anhydride and cyclopentadiene. Hydrolysis of 6 led to α-phenylthio carboxylic acid 14.     

Iodine as novel reagent for the 1,2-addition of trimethylsilyl cyanide to ketones including α,β-unsaturated ketones

Molecular iodine is found to catalyze efficiently the addition of trimethylsilyl cyanide to a range of simple and functionalized ketones under very mild and convenient conditions to afford the corresponding cyanohydrin trimethylsilyl ethers in excellent yields in a short reaction period with high selectivity. α,β-Unsaturated ketones selectively afford the corresponding 1,2-adducts without the formation of 1,4-adducts under similar reaction conditions.     

Synthesis of spiro-1-pyrazolines by the 1,3-dipolar cycloaddition of exocyclic α,β-unsaturated ketones with diazomethane

1,3-Dipolar cycloadditions of exocyclic α,β-unsaturated ketones 1-22 with diazomethane afforded spiro-1-pyrazolines 23-44 in a diastereospecific reaction. The structure and stereochemistry of each compound synthesised has been elucidated by nmr spectroscopic measurements and other analytical techniques. It has been proven that the stereochemistry of the starting α,β-enones was retained in the course of these cycloadditions.