Transition-metal-catalyzed addition of heteroatom-hydrogen bonds to alkynes.

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Lewis Acids: From Conventional Homogeneous to Green Homogeneous and Heterogeneous Catalysis

Kraitchman has shown that a single isotopic substitution on an atom is sufficient to determine directly the coordinates of that atom with respect to the principal axes of the original molecule. Kraitchman's formulas represent exact solutions of the equations for the equilibrium moments of inertia. However, the effects of the zero‐point vibrations are such that the coordinates obtained by substitution from the ground state moments of inertia I0 are systematically less than r0. These coordinates have here been called r (substitution) or rs, and it is found that rs≃(r0+re)/2, and Is= ∑ imirsi2≃(I0+Ie)/2.In the usual method of solution, the coordinate of one atom is determined from the equation for I0, and therefore the difference I0—Is must be made up by this one coordinate. This introduces a large error in the structures normally determined from ground state constants, and results in variations of 0.01 A in structures determined from different sets of isotopic species. If instead, we obtain the structure on...

A new criterion for the determination of molecular structures from ground state rotational constants

Additions of Organometallic Reagents to C=N Bonds: Reactivity and Selectivity

Anti-Markovnikov addition to alkenes with a neighbouring thioacetal function

[2:1] and [2:2] cycloadducts from N-sulfonylamines and azomethines

Phosphoryl Functionalized Bishomoallyl Alcohols by Ring Opening of Epoxides with Lithiated Allyldiphenylphosphane Oxide

δ-Lactone (–)-malyngolide (1) was synthesized by starting from the optically active epoxide 5. Coupling of derivative 3 with propargyl anion 11 and subsequent metal-catalyzed methylation of the triple bond provided 14 incorporating all the carbon atoms of 1. Cyclization to the acetal 16 was achieved via the epoxidation product 15. Adjustment of the oxidation state and removal of protective groups complete the synthesis of 1.

Synthesis of (—)-Malyngolide

The crystal structure of the title compound has been determined by X-ray diffraction. Crystals are monoclinic, space group P21/c, with Z= 4 in a unit cell of dimensions: a= 7.077, b= 11.644, c= 11.955A, β= 106.74°. The structure was solved by direct phase-determining methods and refined to R 0.030 for 1 860 reflections. Except for the C-methyl groups all non-hydrogen atoms are in a single plane. The positive charge is centred essentially at the N(2) atom and the negative charge at the exocyclic S(2) atom. Solution i.r.measurements and temperature-dependent n.m.r. spectra gave no indication of a dipolar species, but revealed the presence of a 2-isothiocyanato-thiocarboxamide, which is formed from the original dipole by ring-opening; this reaction is reversible.

Cycloaddition reactions of heterocumulenes. Part 8. Crystal structure and valence tautomerism of 5-dimethyliminio-4,4-dimethyl-Δ2-thiazoline-2-thiolate

Ernst Schaumann

Papers

Anti-Markovnikov addition to alkenes with a neighbouring thioacetal function

[2:1] and [2:2] cycloadducts from N-sulfonylamines and azomethines

Phosphoryl Functionalized Bishomoallyl Alcohols by Ring Opening of Epoxides with Lithiated Allyldiphenylphosphane Oxide

Synthesis of (—)-Malyngolide

Cycloaddition reactions of heterocumulenes. Part 8. Crystal structure and valence tautomerism of 5-dimethyliminio-4,4-dimethyl-Δ2-thiazoline-2-thiolate