Acetonyl Group Research Articles

Dimeric alkaloids from the barks of Erythrina variegata as well as their occurrence

Thirteen undescribed dimeric Erythrina alkaloids, named as erythrivarines A1–A13, were isolated from the barks of Erythrina variegata L. and. Their structures were determined on the basis of NMR, UV and mass spectral analyses. Dimeric Erythrina alkaloid with a C-8/8′ linkage in erythrivarine A1 was not yet reported. Representative dimers from titled plant were used to prove their occurrence as natural products by LC − MS detection. Additionally, simultaneous investigation enabled us to propose the natural property of seemingly artificial Erythrina alkaloid with acetonyl group.

One-Pot Synthesis of 2-C-Branched Glycosyl Triazoles by Integrating 1,2-Cyclopropanated Sugar Ring-Opening Azidation and CuAAC Reaction.

A series of 2-C-branched glycosyl triazoles including triazole-tethered oligosaccharides and glycopeptides were synthesized in one pot from 1,2-cyclopropanated sugars or 2'-acetonyl-2-O-Ts-C-furanosides, NaN3, and alkynes using PEG-400 as a single solvent. Nucleophilic ring-opening azidation of 1,2-cyclopropanated sugars (or 2'-acetonyl group 1,2-migration-azidation of C-furanosides) obtained glycosyl azides, which upon reaction with alkynes under CuAAC conditions achieved glycosyl triazoles in good yields and high stereoselectivity without the need to change the solvent and isolate any intermediates.

(±) Erysectin A, a new isoprenylated isoflavone with a rare acetonyl group from Erythrina secundiflora Hassk

(±) Erysectin A (1), a new isoprenylated isoflavone with a rare acetonyl group, along with 15 known compounds including eight isoprenylated isoflavones (2–9), two isoprenylated flavanones (10–11), three flavanones (12–14), a flavone (15), and a chalcone (16), was isolated from the twigs and leaves of Erythrina secundiflora Hassk. Their structures were identified based on their 1 D and 2 D NMR spectral data. All the compounds were isolated from this plant for the first time. Compound 1 showed moderate cytotoxicity on several cancer cell lines.

A Non-Enzymatic Pathway with Superoxide in Intracellular Terpenoid Synthesis.

Non-C5 -units terpenoids (norisoprenoids) with an acetonyl group are widely distributed in nature. However, studies on the biosynthesis of norisoprenoids are scarce. Now, the C33 norisoprenoid, (all-E)-farnesylfarnesylacetone, was identified from Bacillus spp. and it was elucidated for the first time that superoxide mediates the cleavage of menaquinones (vitamin K) to form norisoprenoids in saponification treatment. From in vivo experiments using gene-disrupted Bacillus subtilis strains targeted for enzymes responsible for menaquinone biosynthesis and for superoxide dismutase, it was suggested that the non-enzymatic cleavage (autoxidation) of menaquinone with superoxide resulted in norisoprenoid synthesis in Bacillus cells. Furthermore, the bioactive norisoprenoids, farnesylacetone and phytone, were produced in Bacillus cells by this novel synthesis system.

A Non‐Enzymatic Pathway with Superoxide in Intracellular Terpenoid Synthesis

AbstractNon‐C5‐units terpenoids (norisoprenoids) with an acetonyl group are widely distributed in nature. However, studies on the biosynthesis of norisoprenoids are scarce. Now, the C33 norisoprenoid, (all‐E)‐farnesylfarnesylacetone, was identified from Bacillus spp. and it was elucidated for the first time that superoxide mediates the cleavage of menaquinones (vitamin K) to form norisoprenoids in saponification treatment. From in vivo experiments using gene‐disrupted Bacillus subtilis strains targeted for enzymes responsible for menaquinone biosynthesis and for superoxide dismutase, it was suggested that the non‐enzymatic cleavage (autoxidation) of menaquinone with superoxide resulted in norisoprenoid synthesis in Bacillus cells. Furthermore, the bioactive norisoprenoids, farnesylacetone and phytone, were produced in Bacillus cells by this novel synthesis system.

Addition of phthalimide and acetone to phosphorylated methylene quinones

New method for synthesis of phosphorylated methylene quinones via bromination of the sterically hindered phenol [prepared via benzylation of secondary chlorophosphines with 4-(methoxymethyl)-2,6-di-tert-butylphenol] with N-bromosuccinimide followed by dehydrobromination with trimethyl orthoformate has been developed. Tertiary phosphine oxides containing the fragment of sterically hindered phenol and amine or acetonyl group have been synthesized for the first time in the reaction of phosphorylated methylene quinones with N- and C-nucleophiles.

Crystal structures of vasicinone and peganidine hydrochloride

Crystal structures of the alkaloids vasicinone and peganidine hydrochloride were studied by x-ray structure analysis. The configurations of asymmetric centers C4 and C9 in peganidine were determined. The hydroxyl and acetonyl groups were mutually syn-positioned relative to the tricyclic plane. H-bonds involving the Cl ion, which connected molecular cations transformed by 21 screw axes, were formed in the peganidine hydrochloride crystal. H-bonds between the C4 carbonyl and the C9 hydroxyl transformed by a glide plane were formed in the vasicinone crystal. The N1 atom was not involved in forming intermolecular H-bonds.

(Pyrazolylmethyl)pyridine platinum(II) and gold(III) complexes: Synthesis, structures and evaluation as anticancer agents

Reactions of 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine ( L1), 2-(3,5-diphenylpyrazol-1-ylmethyl)pyridine ( L2), 2-(3,5-di- tert-butylpyrazol-1-ylmethyl)pyridine ( L3) and 2-(3- p-tolylpyrazol-1-ylmethyl)pyridine ( L4) with K 2[PtCl 4] in a mixture of ethanol and water formed the dichloro platinum complexes [PtCl 2( L1)] ( 1), [PtCl 2( L2)] ( 2), [PtCl 2( L3)] ( 3) and [PtCl 2( L4)] ( 4). Complex 1, [PtCl 2( L1)], could also be prepared in a mixture of acetone and water. Performing the reactions of L2 and L3 in a mixture of acetone and water, however, led to C–H activation of acetone under mild conditions to form the neutral acetonyl complexes [Pt(CH 2COCH 3)Cl( L2)] ( 2a) and [Pt(CH 2COCH 3)Cl( L3)] ( 3a). The same ligands reacted with HAuCl 4 · 4H 2O in a mixture of ethanol and water to form the gold salts [AuCl 2( L1)][AuCl 4] ( 5) [AuCl 2( L2)][Cl] ( 6) [AuCl 2( L3)][Cl] ( 7) and [AuCl 2( L4)][AuCl 4] ( 8); however, with the pyrazolyl unit in the para position of the pyridinyl ring in 4-(3,5-dimethylpyrazol-1-ylmethyl)pyridine ( L5), 4-(3,5-diphenylpyrazol-1-ylmethyl)pyridine ( L6) neutral gold complexes [AuCl 3( L5)] ( 9) and [AuCl 2( L6)] ( 10) were formed; signifying the role the position of the pyrazolyl group plays in product formation in the gold reactions. X-ray crystallographic structural determination of L6, 2, 3 3a, 8 and 10 were very important in confirming the structures of these compounds; particularly for 3a and 8 where the presence of the acetonyl group confirmed C–H activation and for 8 where the counter ion is AuCl 4 - . Cytotoxicity studies of L2, L4 and complexes 1– 10 against HeLa cells showed the Au complexes were much less active than the Pt complexes.

A New Series of Non‐Classical Type C Heteropentalenes: 2H‐Pyrrolo[2,1‐c][1,2,4]triazoles.

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Identification of a novel 7-desmethyl-7-acetonyl bacteriophaeophorbide c series in a recent sediment

We report the identification of three members of a novel 7-desmethyl-7-acetonyl bacteriopheophorbide c series isolated from a coastal salt pond sediment (Salt Pond, MA, USA), as well as the full structure determination ( 1H NMR) of one of the members. The compounds have the same carbon framework as bacteriopheophorbides c but bear an acetonyl group at C-7. They may be fossils of an unknown photosynthetic pigment series and could be intermediates in the formation of some porphyrins isolated previously from ancient sediments.

A new series of non‐classical type C heteropentalenes: 2H‐pyrrolo[2,1‐c][1,2,4]triazoles

Abstractmagnified image7‐Functionalized title compounds 5 are obtained by cyclization of 3‐acetonyl‐ or 3‐[(alkoxycarbonyl)‐methyl]‐4‐phenacyl‐1,2,4‐triazolium salts 2 having methyl at C(5) the process can be effected in an acetate buffer or by base, irrespective of the function at C(3). 5‐Unsubstituted salts 2 do not react unless the side chain at C(3) is an acetonyl group. Cyclization of 2 with acetic anhydride‐base gives rise to 5,7‐difunctionalized compounds 8; again methyl at C(5) of 2 is compulsory, but here the reaction can be extended to salts having an (alkoxycarbonyl)methyl group at C(4). Regarding defunctionalization, acetyl groups can be split from C(5) only, whereas ester functions are removable also from C(7). Title compounds devoid of acceptor groups (XIII) are unstable but can be trapped by electrophilic reagents (DMAD, acetic anhydride, and phenyl isocyanate) to give the derivatives 10 and 12. The 7‐functionalized products 5 are likewise susceptible to SE‐reactions. By comparison, all title compounds appear to be more reactive toward this kind of reagents than the isomeric 1H‐pyrrolotriazoles (13) including 2H‐pyrrolotetrazoles (III). This is consistent with B3LYP‐DFT calculations using appropriate models.

Palladium catalysed hydroethoxycarbonylation in imidazolium-based ionic liquids

Imidazolium-based ionic liquids with [PF 6] −, [BF 4] − and [GaCl 4] − counterions have been synthesised and used in hydroethoxycarbonylation of styrene. In addition to the formation of the expected ethyl 2-phenyl- and 3-phenyl-propionates, the oligomerization (polymerization) of the substrate depending on the counterion of the ionic liquid was also observed. Moderate to high regioselectivities towards branched esters have been obtained with the ‘preformed’ PdCl 2(PPh 3) 2 catalyst. The addition of 1,1′-bis(diphenylphosphino)ferrocene (dppf) favoured the formation of the linear isomer, however, complete linear regioselectivity has been obtained only in acetonyl-methyl-imidazolium hexafluorophosphate. It was found that the regioselectivity is strongly influenced by the structure of the ionic liquid: in [BMIM][PF 6] the formation of the linear ester is slightly favoured, however, the substitution of the butyl substituent with benzyl or acetonyl group resulted in complete branched selectivity.

Crystal structure of the novel neutral octahedral complex [(4′-(4- tbutylphenyl)-2,2′:6′,2″-terpyridine)Rh III(Br)(acetonyl) 2

The synthesis and the crystal and molecular structure of a unique Rh(III) complex, [Rh III(Br)(acetonyl) 2(4′-(4- tbutylphenyl)-2,2′:6′,2″-terpyridine)] ( 1) are described. The yellow crystals separate from the acetone solution of the starting complex [Rh(Br)(COD)] 2 and the ligand 4′-(4- tbutylphenyl)-2,2′:6′,2″-terpyridine after standing at room temperature for a prolonged period of time. The crystals are almost insoluble in all common organic solvents. The single-crystal X-ray structure determination shows that compound 1 is the first Rh-complex with a terdentate nitrogen ligand and two axially oriented, σ-bound acetonyl groups. DFT-calculations on a model complex without the substituent on the terpyridine ligand were carried out and agree very well with the X-ray results, confirming the constitution and geometry of the molecule.

X-ray diffraction and total 1 H and 13 C NMR assignment of ( RS )-5,6-dihydro-7,8-dimethoxy-5-methyl-6-(2-oxopropyl)-(2,3-methylenedioxyphenyl)-[c]-phenanthridine (( RS )-6-acetonyldihydrochelerythrine)

The X-ray diffraction structure of (RS)-5,6-dihydro-7,8-dimethoxy-5-methyl-6-(2-oxopropyl)-(2,3-methylenedioxyphenyl)-[c]-phenanthridine ((RS)-6-acetonyldihydrochelerythrine), isolated as an artifact from Bocconia Arborea, is reported. This compound crystallizes as orthorhombic system, space group Pna21, with a = 13.216(2) A, b = 7.6547(10) A, c = 20.096(3) A. The phenanthridine central ring presents a distorted boat conformation, which gives rise to two planes with 21.30° between them. The acetonyl group at the six position forms weak C — H ⋯ O and C — H ⋯ π-ring interactions. The title compound was completely characterized in solution by 1H and 13C and 2D NMR experiments.

Polymer-supported preparation of substituted phenols: A new example of simultaneous cyclization-cleavage reaction on solid phase

A series of variously substituted phenols was synthesized in high yields using the “cyclization-cleavage” approach. Base-catalyzed reactions between α,β-unsaturated ketones and polymer-bound acetonyl groups result in a tandem Michael addition/annulation reaction followed by elimination and rearrangement into phenols. Since all intermediates are on the resin until the last stage, the final reaction products contain only the desired phenols with the starting ketones as minor impurities. This efficient one-pot aromatic ring formation represents a new variant of solid phase synthesis.

The reactions of two σ-anionic compounds (Jackson–Meisenheimer adducts) in liquid ammonia studied by13C nuclear magnetic resonance spectroscopy

The reactions of the Jackson–Meisenheimer adducts derived from: (a) methoxide ion and 1,3,5-trinitrobenzene; (b) acetone carbanion and 1,3,5-trinitrobenzene, in liquid ammonia solution have been studied by 13C n.m.r. With the adduct (a) the methoxy group is labile as expected, whereas with (b) the C–C bond on the ring sp3 carbon atom remains unbroken, but cyclisation through the γ-carbon of the acetonyl group occurs to form a bicyclo-derivative.

Chemical Study of Alkaloids from Corydalis conspersa

From the whole plant of CORYDALIS CONSPERSA, four benzo[ C]-phenanthridine-type alkaloids were isolated. Three of these were identified as corynoline, acetylcorynoline and corynoloxine. The fourth is a new alkaloid, named consperine. Its structure, C (26)H (27)NO (7), has been established to be 6-acetonylacetylcorynoline on the basis of spectral data and chemical synthesis. The configuration of acetonyl group in consperine is also discussed.

A Convenient One-Step Synthesis of 1,4-Diketones

Abstract In the last few years, numerous efforts have been directed to the development of acetonylation methods1. Recent works in this laboratory have shown that O, O-t-butyl and O-isopropenyl peroxycarbonate 1 can be regarded as a good acetonylation reagent; its decomposition in solution results in the substitution of an hydrogen atom by an acetonyl group on each compound Σ-H able to undergo free radical addition reactions to alkenes2. The following free radical chain reaction mechanism has been proposed:

Alkylation of quinones by carbanions: use of pyridinium ylides to insert phenacyl, acetonyl and related groups

Reports that carbanions C– add to quinones Q in the ratios 1:1 and 2:1 are confirmed; even if an excess of quinone is present, cage or bridge products are formed only if the carbanion is itself quinonoid. Pyridinium salts C5H5[graphic omitted]CH2COR X– react with quinones in mildly basic solvents to give acetonylquinones and other quinones containing the group RCOCH2.

Synthesis and photochromic properties of indolinospirochromenes with benzyl, ethyl, and acetonyl groups attached to the nitrogen atom

A number of photochromic indoline spirochromenes with benzyl, acetonyl, and ethyl substituents attached to the nitrogen atom in the indoline part of the molecule were synthesized. The introduction of a benzyl group at the nitrogen atom in place of a methyl group does not change the rate constants of the dark decolorization of the photomerocyanines, whereas an acetonyl group increases them, and an ethyl group decreases them. The introduction of the indicated substituents in the 1 position gives rise to a bathochromic shift (up to 18 nm) of the long-wave absorption band of the merocyanine form of the spirochromene.