Ni-Catalyzed Alkenylation of Ketone Enolates under Mild Conditions: Catalyst Identification and Optimization.

A procedure for Ni-catalyzed cross-coupling of ketone enolates with alkenyl halides has been developed. Intermolecular coupling of aromatic and aliphatic ketone lithium enolates with a variety of alkenyl halides is achieved in the presence of Ni(cod)2 catalyst (5 mol %), an N-heterocyclic carbene (NHC) ligand, and LiI (10 mol %) at 6-22 °C for 0.5-12 h with yields of up to 90%.

Palladium-catalyzed alkenylation of ketone enolates under mild conditions.

A protocol for a mild, catalytic, intermolecular alkenylation of ketone enolates has been developed using a Pd/Q-Phos catalyst. Efficient intermolecular coupling of a variety of ketones with alkenyl bromides was achieved with a slight excess of LiHMDS and temperatures down to 0 °C.

Selective cleavage of 3,5-bis-(trifluoromethyl)benzylcarbamate by SmI2-Et3N-H2O.

A novel electron poor protection group for amines has been developed. It undergoes rapid cleavage by SmI2-Et3N-H2O and its orthogonality towards the regular benzyl carbamate group (CBz) under reductive or transfer hydrogenolytic conditions is reported.

Solvent dependent reductive defluorination of aliphatic C-F bonds employing Sm(HMDS)2.

Sm(HMDS)(2) in n-hexane mediates fast cleavage of primary, secondary and tertiary alkyl fluorides in good to excellent yields. In n-hexane Sm(HMDS)(2) exhibits uniquely enhanced reductive ability towards the C-F bond compared to when using THF as solvent.

Palladium- and nickel-catalyzed alkenylation of enolates.

Transition-metal-catalyzed alkenylation of enolates provides a direct method to synthesize broadly useful β,γ-unsaturated carbonyl compounds from the corresponding carbonyl compound and alkenyl halides. Despite being reported in the early seventies, this reaction class saw little development for many years. In the past decade, however, efforts to develop this reaction further have increased considerably, and many research groups have reported efficient coupling protocols, including enantioselective versions.

Selective α-defluorination of polyfluorinated esters and amides using SmI2/Et3N/H2O.

SmI(2)/H(2)O promotes selective α-monodefluorinations, while addition of an amine results in complete α-defluorination reactions.

KHMDS enhanced SmI(2)-mediated reformatsky type alpha-cyanation.

A novel combination of SmI(2), KHMDS, and TsCN can be utilized to introduce a cyano group into structurally diverse and highly sensitive 2-alkyl-chroman-4-ones. Subsequent oxidation allows the formed 2-alkyl-3-cyanochromones to be isolated in yields ranging from 49 to 77%. In addition, alpha-bromoketones and esters were found to undergo equally effective alpha-cyanation.

Instantaneous deprotection of tosylamides and esters with SmI(2)/amine/water.

SmI(2)/amine/water mediates instantaneous cleavage of tosyl amides and tosyl esters. Highly hindered, sensitive and functionalized substrates were successfully deprotected in near quantitative yield.

Propylphenols are metabolites in the anaerobic biodegradation of propylbenzene under iron-reducing conditions.

The metabolism of monoaromatic hydrocarbons by an iron-reducing bacterial enrichment culture originating from diesel-contaminated groundwater was examined using d7-propylbenzene as a model hydrocarbon. Sequence analysis of the 16S rDNA gene showed that the dominant part (10 of 10 clones) of the enrichment culture consisted of a bacterium closely related to clones found in benzene-contaminated groundwater and to the iron-reducing beta-proteobacterium, Rhodoferax ferrireducens (similarity values were 99.5% and 98.