Tuning diastereoisomerism in platinum(ii) phosphino- and aminothiolato hydrido complexes

Tuning between the cis and trans Pt(ii) based complexes bearing phosphinothiolato and aminothiolato ligands.

Cyclic Metalated Nitriles: Stereoselective Cyclizations to cis- and trans-Hydrindanes, Decalins, and Bicyclo[4.3.0]undecanes

Metalated nitriles are nucleophilic chameleons whose precise identity is determined by the nature of the metal, the solvent, the temperature, and the structure of the nitrile. The review surveys the different structural types and their cyclization trajectories to show how to selectively tune the metalated nitrile geometry for stereoselective cyclizations to a variety of cis or trans hydrindanes, decalins, and bicyclo[4.3.0]undecanes.

Metalated Nitriles: Stereodivergent Cation-Controlled Cyclizations1

Stereodivergent cyclizations of gamma-hydroxy cyclohexanecarbonitriles are controlled simply through judicious choice of cation in the alkylmetal base. Deprotonating a series of cyclic gamma-hydroxy nitriles with i-PrMgBr generates C-magnesiated nitriles that cyclize under stereoelectronic control to cis-fused hydrindanes, decalins, and bicyclo [5.4.0] undecanes. An analogous deprotonation with BuLi triggers cyclization to trans-fused hydrindanes, decalins, and bicyclo [5.4.0] undecanes consistent with a sterically controlled electrophilic attack on an equatorial nitrile anion. Using cations to control the geometry of metalated nitriles provides a versatile, stereodivergent cyclization to cis- and trans-hydrindanes, decalins, and [5. 4. 0] undecanes, and reveals the key geometric requirements for intramolecular S(N)2 and S(N)2' displacements.

Metalated Nitriles: Chelation-Controlled Cyclizations to cis and trans Hydrindanes and Decalins

Chelation provides a powerful means of stereocontrol in alkylations of metalated nitriles. Doubly deprotonating a series of cyclic beta-hydroxynitriles triggers cyclizations that implicate metalated nitrile intermediates having configurations imposed by chelation with an adjacent, chiral lithium alkoxide. Identifying chelation as a general stereocontrol element explains several previously anomalous alkylations of metalated nitriles and provides a potential solution to the long-standing difficulty of synthesizing trans-hydrindanes. Employing chelation to control the metalated nitrile geometry permits selective cyclizations to cis and trans hydrindanes and decalins and provides key insight into the geometrical requirements of these demanding cyclizations.

Nucleophilic addition of hydroxylamine, methoxylamine, and hydrazine to malononitrileoxime

The chemistry of malononitrileoxime, HONC(CN)(2), with respect to nucleophilic addition to ammonia, methylamine, hydroxylamine, methoxylamine, and hydrazine is reported. Whereas the poorly nucleophilic ammonia and methylamine do not react, hydroxylamine, methoxylamine, and hydrazine add to the nitrile groups of the oxime, yielding the corresponding amidoximes and amidrazones. Depending on the stoichiometry of the reactions, hydroxylamine and hydrazine add to one or both of the nitrile groups; methoxylamine adds to only one of the nitrile groups. Three of the products, namely, cyanoacetamidoxime (1), 3-amino-2,3-hydroxyiminopropionitrile monohydrate (2.H(2)O), and 3,5-diaminopyrazolone-4-oxime monohydrochloride monohydrate (6.HCl.H(2)O), are characterized by single-crystal X-ray diffraction data. All of the products exhibit exothermic decomposition properties with heats of decomposition in the range of 500-1500 kJ mol(-)(1).