Controlled synthesis of CDH-ketones.

The synthesis of compounds containing partially deuterated groups such as CDH lacks general methods. These compounds could be important for fine control of metabolic processes in drug discovery, or in the development of multifunctional probes for analysis by complementary spectroscopic techniques. Here, a convenient route to CDH-methyl ketones is reported through coupling of esters with bis[(pinacolato)boryl]methane and trapping with DO.

Assessing the rigidity of cubanes and bicyclo(1.1.1)pentanes as benzene bioisosteres.

Aromatic rings are critical core substructures in the majority of pharmaceutical compounds. There is much recent interest in replacing aromatic structures with saturated bioisosteres of benzene, which are generally fused or bridged ring systems. These bioisosteres often show improved solubility properties compared to benzene, and may also undergo fewer unwanted metabolic processes.

Effects of Replacing Oxygenated Functionality with Fluorine on Lipophilicity.

The replacement of oxygenated functionality (hydroxy and alkoxy) with a fluorine atom is a commonly used bioisosteric replacement in medicinal chemistry. In this paper, we use molecular matched-pair analysis to better understand the effects of this replacement on lipophilicity. It seems that the reduced log of the oxygenated compound is normally dominant in determining the size of this difference.

Fluorinated carboxylic acids as powerful building blocks for the formation of bimolecular monolayers.

We compare the ability of a prototypical dicarboxylic acid and its fluorinated analogue to act as molecular building blocks for the formation of self-assembled monolayers. Whilst fluorination is found to prevent homomolecular self-assembly, it greatly increases the ability of the carboxylic acid to act as a hydrogen bond donor for the formation of bimolecular networks.

Fluorination of organoboron compounds.

Methods for the fluorination of organoboron compounds are described. This review will cover the fluorination of aromatic and aliphatic systems using both electrophilic and nucleophilc sources of fluorine. Emerging methods for radiofluorination using 18F for the synthesis of PET-imaging agents are also described.

Conformational preferences of α-fluoroketones may influence their reactivity.

Fluorine has been shown in many cases to impart specific and predictable effects on molecular conformation. Here it is shown that these conformational effects may have an influence on reactivity through studying the relative reactivity of various α-halogenated ketones towards borohydride reduction. These results demonstrate that the α-fluoro ketones are in fact a little less reactive than the corresponding α-chloro and α-bromo derivatives.

A Coupling Approach for the Generation of α,α-Bis(enolate) Equivalents: Regioselective Synthesis of gem-Difunctionalized Ketones.

Regioselective α,α-difunctionalization adjacent to a ketone is a significant synthetic challenge. Here, we present a solution to this problem through the transition-metal-free coupling of esters with geminal bis(boron) compounds. This forms an α,α-bis(enolate) equivalent which can be trapped with electrophiles including alkyl halides and fluorinating agents.

Transition-Metal-Free Homologative Cross-Coupling of Aldehydes and Ketones with Geminal Bis(boron) Compounds.

We report a transition-metal-free coupling of aldehydes and ketones with geminal bis(boron) building blocks which provides the coupled, homologated carbonyl compound upon oxidation. This reaction not only extends an alkyl chain containing a carbonyl group, it also simultaneously introduces a new carbonyl substituent. We demonstrate that enantiopure aldehydes with an enolizable stereogenic center undergo this reaction with complete retention of stereochemistry.

Rh-Catalyzed arylation of fluorinated ketones with arylboronic acids.

The Rh-catalyzed arylation of fluorinated ketones with boronic acids is reported. This efficient process allows access to fluorinated alcohols in high yields under mild conditions. Competition experiments suggest that difluoromethyl ketones are more reactive than trifluoromethyl ketones in this process, despite their decreased electronic activation, an effect we postulate to be steric in origin.

One-pot synthesis of difluoromethyl ketones by a difluorination/fragmentation process.

Difluoromethyl ketones are an under-studied class of ketones which have great potential as useful building blocks for materials and drug design. Here we report a simple and convenient synthesis of this class of compounds via a one-pot difluorination/fragmentation of 1-trifluoromethyl-1,3-diketones which should now allow the chemistry of difluoromethyl ketones to be fully developed.

A second-generation ligand for the enantioselective rhodium-catalyzed addition of arylboronic acids to alkenylazaarenes.

A 2,4,6-trialkylanilide-containing chiral diene has been identified as a superior ligand for the enantioselective rhodium-catalyzed arylation of alkenylazaarenes with arylboronic acids.

Enantioselective Rh(I)-catalyzed cyclization of arylboron compounds onto ketones.

Rhodium complexes based upon chiral sulfinamide-alkene, TADDOL-derived phosphoramidite, or diene ligands catalyze cyclizations of arylboron compounds onto ketones, generating a variety of products containing five-, six-, or seven-membered rings with good yields and high enantioselectivities.

9,10-Dioxa-1,2-diaza-anthracene derivatives from tetrafluoropyridazine.

Reaction of tetrafluoropyridazine with catechol gives a tricyclic 9,10-dioxa-1,2-diaza-anthracene system by a sequential nucleophilic aromatic substitution ring annelation process, further extending the use of perfluoroheteroaromatic derivatives for the synthesis of unusual polyfunctional heterocyclic architectures. The tricyclic scaffold reacts with amines and sodium ethoxide providing a short series of functional 9,10-dioxa-1,2-diaza-anthracene systems.

Polysubstituted pyridazinones from sequential nucleophilic substitution reactions of tetrafluoropyridazine.

4,5,6-trifluoropyridazin-3(2H)-one can be used as a scaffold for the synthesis of various 4,5- and 4,6-disubstituted and ring-fused pyridazinone systems by sequential nucleophilic aromatic substitution processes. Although the regioselectivity of nucleophilic substitution can be affected by the nature of the nucleophile and the substituent attached to the pyridazinone ring, a variety of polyfunctional systems can be readily accessed by sequential nucleophilic substitution methodology which may have applications in the drug discovery arena. For example, reaction of 4,5,6-trifluoropyridazin-3(2H)-one with nitrogen nucleophiles leads to a mixture of aminated products arising from substitution of fluorine located at the 4- and 5-positions.