Efficient synthesis of tetradecafluoro-4-phenylheptan-4-ol by a Cannizzaro-type reaction and application of the alcohol as a bulky Martin ligand variant for a new anti-apicophilic phosphorane

Organohypervalent heterocycles

This review summarizes the structural and synthetic aspects of heterocyclic molecules incorporating an atom of a hypervalent main-group element. The term "hypervalent" has been suggested for derivatives of main-group elements with more than eight valence electrons, and the concept of hypervalency is commonly used despite some criticism from theoretical chemists. The significantly higher thermal stability of hypervalent heterocycles compared to their acyclic analogs adds special features to their chemistry, particularly for bromine and iodine. Heterocyclic compounds of elements with double bonds are not categorized as hypervalent molecules owing to the zwitterionic nature of these bonds, resulting in the conventional 8-electron species. This review is focused on hypervalent heterocyclic derivatives of nonmetal main-group elements, such as boron, silicon, nitrogen, carbon, phosphorus, sulfur, selenium, bromine, chlorine, iodine(III) and iodine(V).

Chemoenzymatic total synthesis of nodulones C and D using a naphthol reductase of Magnaporthe grisea

Herein, the asymmetric and chemoenzymatic synthesis of (R)-nodulone C, cis-nodulone D and related (R)-dihydronaphthalenone is reported. It involves multistep chemical synthesis of putative biosynthetic substrates followed by regio- and stereoselective reduction using a NADPH-dependent tetrahydroxynaphthalene reductase of Magnaporthe grisea to obtain chiral nodulones in a biomimetic fashion.

Synthesis of trifluoromethyl ketones by nucleophilic trifluoromethylation of esters under a fluoroform/KHMDS/triglyme system

A straightforward method that enables the formation of biologically attractive trifluoromethyl ketones from readily available methyl esters using the potent greenhouse gas fluoroform (HCF₃, HFC-23) was developed. The combination of fluoroform and KHMDS in triglyme at −40 °C was effective for this transformation, with good yields as high as 92%. Substrate scope of the trifluoromethylation procedure was explored for aromatic, aliphatic, and conjugated methyl esters. This study presents a straightforward trifluoromethylation process of various methyl esters that convert well to the corresponding trifluoromethyl ketones. The tolerance of various pharmacophores under the reaction conditions was also explored.

Synthesis and characterization of a pair of O-fac/O-mer 12-P-6 alkyloxaphosphates with a P-O-C-C four-membered ring

The synthesis and characterization of a stereoisomer pair of 12-P-6 alkyloxaphosphates synthesised from pentacoordinate phosphoranes.

Structurally characterized hexacoordinate organophosphorus compounds remain rare due to their highly reactive nature and thermal instability. Herein we report the first synthesis of a pair of O-facial and O-meridional hexacoordinate oxaphosphates (5B and 5D) obtained from the O-apical and O-equatorial β-hydroxyalkylphosphoranes 3 and 4. This was achieved by using the bulky C₂F₅-groups on the ortho-substituted aryl backbone. Calculations of the relative energies of possible isomers indicate 5B and 5D are thermodynamic products. Although the mechanisms of their formation and the determining factor of stereo-selectivity are still unclear, their isolation and structure conformation contributes to a formulation of a viable strategy for diastereoselective synthesis of heteroleptic hexacoordinate organophosphates.

Chiral Hypervalent, Pentacoordinated Phosphoranes

This review presents synthetic procedures applied to the preparation of chiral (mainly optically active) pentacoordinated, hypervalent mono and bicyclic phosphoranes. The mechanisms of their stereoisomerization and their selected interconversions are also presented.

A ligand-free strategy for the copper-catalysed direct alkynylation of trifluoromethyl ketones

A superbase-induced copper-catalyzed direct alkynylation method for trifluoromethyl ketones was developed without any additional ligand under mild conditions.

Synthesis and characterization of antiapicophilic arsoranes and related compounds

Utilizing bulky bidentate ligand systems with C(2)F(5) and n-C(3)F(7) groups, antiapicophilic arsoranes (5b and 5c, respectively) were synthesized. A kinetic study on the isomerization of these arsoranes to their more stable isomers showed that the barriers increased in the order of CF(3) < C(2)F(5) < n-C(3)F(7) in accord with their steric bulk. It was also revealed that the degree of freezing isomerization was larger for the change from CF(3) to C(2)F(5) than from C(2)F(5) to n-C(3)F(7), obvious from the differences in activation free energy at 363 K of 1.6 and 0.3 kcal mol(-1), respectively. X-ray structural analysis of several precursors of these two systems disclosed the unique structures of these compounds.