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The synthesis of the 2-oxoethyl- and 2-chloroethyl derivatives of 2,2'-sulfonylbis(3-(benzylamino)-(E,E)-N-propenamides) (SBBOP and SBBCP) provides improved hemoglobin cross-linking reagents. The two are prepared in 14.7% and 34% respective yields from dimethyl 2,2'-sulfonyldiacetate by a six-step convergent process. An alternative four-step route from the same substrate produces SBBCP in 65% yield. Subsequent X-ray studies show the SBBOP and SBBCP have a tether distance of 9.18 angstroms, enough to place them within hemoglobin's DPG pocket for cross-linking.

Binding of a calix[5]arene containing a single phosphorous ligand and three hydroxyl groups, calix[5]PNMe2(OH)3 toward titanium and zirconium is investigated to understand the factors that determine the strength of the phosphorous/metal interaction within the constraint of the calix[5]arene. The two most important aspects controlling the phosphorus/metal contact are the metal, with the larger zirconium showing stronger interaction, and the calix[5]arene conformation, with the cone conformation showing the weaker interaction.

The synthesis of new bis(pyridylethynyl) ligands is investigated in which the two pyridylethynyl moieties are separated by organosilicon spacers. The difference in flexibility between the two spacers is apparent on examination of the various bond angles in the complexes.

The calix[4]arene derivatives containing both four- and five-coordinate silicon and phosphorus, conformational isomerism of several of these species, and a unique solvent dependent coordination change for silicon are described. The structural data allow comparison between isoelectronic silicon and phosphorus geometries as well as explains the relationship between four- and five-coordinate structures.

The dianions, N-(4'-methoxyphenyl)-2-butenamide and 2-butenoic acid, undergo tandem-addition rearrangements with 3,6-dimethylbenzyne and 3,4,5, 6-tetramethylbenzyne to produce adequate yields of rearranged ring intermediates. The process involves the formation of an aryne-nitrile anion adduct and its subsequent conversion to a benzocyclobutane derivative which eventually undergoes ring opening to afford rearranged benzyl dianions. The spectroscopic and X-ray crystallographic analyses have confirmed the structures of the products.

Binding of a calix[5]arene containing a single phosphorus ligand and three hydroxyl groups, calix[5]PNMe2(OH)3, 1, toward titanium and zirconium is investigated to yield insight into the factors that determine the strength of the phosphorus/metal interaction within the constraint of the calix[5]arene. Treatment of 1 with tetrakis(dimethylamino)-titanium yields three complexes, 4a, 4b, and 4c, each of which shows the loss of 3 tool of dimethylamine in the reaction with the titanium bound to three oxygens. Treatment of 1 with tetrakis(diethylamino)zirconium proceeds similarly, although only two products, 5a and 5b, were isolated. X-ray structures of the products were obtained. Complexes 4a and 5a show similar geometries, with the calix[5]arene in an approximate cone conformation and the phosphorus lone pair directed toward the metal. The P⋯M distances are, however, markedly different: 3.69 Å in 4a and 3.18 Å in 5a, the former indicative of no interaction and the latter a weak one. Complexes 4b and 5b each are dimers, featuring a planar four-membered M-O-M-O ring; however, the titanium is five-coordinate in 4b with no phosphorus/metal bond, while the zirconium in 5b is six-coordinate with a P-Zr distance of 2.95 Å. Complex 4c is monomeric with the calix[5]arene in an approximate 1,2-alternate conformation with a P⋯Ti distance of 2.90 Å. The two most significant aspects controlling the phosphorus/metal contact are the metal, with the larger zirconium showing stronger interaction, and the calix[5]arene conformation, with the cone conformation showing the weaker interaction. [ABSTRACT FROM AUTHOR]

Reports on the first reactions on the methyl groups of cyclic nongeminal methylphenylphosphazene trimers. Deprotonation-substitution reactions; Thermal properties; X-ray structure studies of cyclophosphazenes.

Heating pure samples of the cyclic phosphazenes, cis- or trans-[Me(Ph)PN][sub3], yielded mixtures of the cis and trans isomers of the cyclic phosphazene trimers, [Me(Ph)PN][sub3], and all four geometric isomers of the tetramers, [Me(Ph)PN][sub4]. Varying the temperature and heating times changes the ratio of these components. Following the thermolysis by NMR spectroscopy indicated that only a mixture of the two isomeric trimers occurred initially. Longer heating times produced mixtures of the isomers of the tetramer. Column chromatography and solubility differences were used to separate each of the isomers of the tetramer. Spectroscopic and X-ray crystallographic studies suggest that the four different geometrical isomers of the tetramer can be described as cone, partial cone, 1,2-alternate, and 1,3-alternate by analogy to calix[4]-arene. [ABSTRACT FROM AUTHOR]

Reports on the validation of a highly stereoselective synthesis of (Z)-α-haloacrylates via Cr(II)-mediated olefination of aldehydes with commercial trihaloacetates. Preparation of (Z)-α-fluoro, (Z)-α-chloro and (Z)-α-bromo-acrylates in excellent yields with unprecedented stereocontrol; Isolation of the dihalohydrin intermediate.