5a-Butyl-1,3,8,10-tetra-chloro-7,13-bis-(4-nitro-benzo-yl)-5a,6a,12a,12b-tetra-hydro-7H,13H-thieno[2,3-b:4,5-b']bis-(1,4-benzoxazine)

The title compound, C(34)H(24)Cl(4)N(4)O(8)S, is a linear penta-cyclic system formed of two substituted benzoxazinyl groups fused to 2-n-butyl-tetra-hydro-thio-phene. The oxazine ring, which is fused to the n-butyl-substituted side of the thio-phene ring, is in a boat conformation. The other fused oxazine ring and the tetra-hydro-thiene ring are each in an envelope conformation. The bridgehead C atom alpha to both the S and N atoms forms the flap of each envelope. This results in a twist of the penta-cyclic system such that the dihedral angle between the terminal dichloro-benzene rings is 82.92 (8)°. In the crystal, inversion-related mol-ecules form a weakly hydrogen-bonded dimer, with two C-H⋯O inter-actions between an H atom on the oxazine ring and an amide O atom. Additionally, C-H⋯O inter-actions occur between an H atom on a screw-related nitro-benzene ring and an O atom on the nitro-benzene ring of one mol-ecule. One of the Cl atoms and the butyl group are disordered over two sets of sites with occupancy ratios of 0.94 (2):0.06 (2) and 0.624 (4):0.376 (4), respectively.

Microwave-Assisted Bond Forming Reactions

ABSTRACT FOR PART I: PHOSPHA-MICHAEL ADDITIONS TO ACTIVATED INTERNAL ALKENES: STERIC AND ELECTRONIC EFFECTS A method for the phospha-Michael addition of bis(4-methyl)phenyl phosphine oxide to activated internal alkenes has been developed. Michael acceptors including cinnamates, crotonates, chalcones, and internal alkenes containing multiple activating groups were all successfully utilized in this reaction. The reaction was fairly tolerant of electron-donating and electron-withdrawing substituents on the Michael acceptor, and moderate to excellent yields (49-96%) of the adducts were isolated. When steric bulk was increased by a second substituent on the -position of the Michael-acceptor the reaction was suppressed. This was usually overcome by adding a second activating substituent to the -position. ABSTRACT FOR PART II: MICROWAVE-ASSISTED ARYLGOLD BOND FORMATION A microwave-assisted method was developed for the formation of arylgold complexes containing (2-Biphenyl)di-tert-butylphosphine (JohnPhos) as the supporting phosphine ligand. Arylboronic acids with increasingly bulky aromatic groups were screened to determine the steric limitations of the reaction. Arylgold complexes (JohnPhos)Au(p-methoxyphenyl), (JohnPhos)Au(2,4,6-trimethylphenyl), and (JohnPhos)Au(4-bromo-10-anthracene) were all synthesized by microwave irradiation at 70ºC in the presence of Cs2CO3 in either THF or iPrOH. Reactions performed with arylboronic acids containing unhindered ortho positions were carried out in THF. Arylboronic acids with substituents on the ortho position required iPrOH as the reaction solvent. Arylboronic acids with extreme steric hindrance on the ortho position of the aryl substituent, 2,4,6-triisopropylpphenylboronic acid, were unreactive. It was determined that increasing the irradiation temperature increased the formation of side products, therefore to promote conversion to the arylgold complex the duration of the reaction time was increased while maintaining a temperature of 70ºC. Arylgold complexes (JohnPhos)Au(p-methoxyphenyl), (JohnPhos)Au(2,4,6-trimethylphenyl), and (JohnPhos)Au(4-bromo-10-anthracene) were synthesized with moderate yields (40-69%).

Solvatochromic and Thermochromic Studies of Tryptanthrin

Solvatochromism and thermochromism describe how a solvent or environment affects the photophysical behavior of a photoluminescent solute. The most common use of solvatochromism is as a probe in which the polarity of a solvent in which a solvatochromic solute is dissolved can be spectroscopically measured. Solvatochromic and thermochromic studies of tryptanthrin in several different solvents are reported. Absorption and corrected emission spectra for tryptanthrin at ~10-6 M concentrations are reported in four aprotic and nine alcoholic solvents. The absorption spectra are relatively unaffected by changes in solvent polarity and by differences in the hydrogen bonding ability of the alcoholic solvents. The emission spectra are much more affected by changes in solvent polarity and hydrogen bonding ability. In aprotic solvents, emission energy decreases and emission intensity increases with increasing solvent polarity. In the alcoholic solvents, emission energy also decreases with increasing solvent polarity. However, emission intensity for the alcoholic solvents varies significantly from the aprotic solvents over similar polarity ranges. This suggests that in the alcoholic solvents, hydrogen bonding ability correlates better than polarity to emission energy and intensity trends. The absorption and emission data in the aprotic solvents were also used to estimate the ground and emitting excited state dipole moments for tryptanthrin. The value obtained for the ground state dipole moment (2.37 D) agrees with theoretical results (2.06 D) and a previously reported experimental value (2.0 D). Attempts to explain previously reported results and conclusions with respect to the solvatochromic behavior of the aromatic carbonyls fluorenone and benzo(b)fluorenone were explored in an attempt to understand the solvatochromic response of tryptanthrin. Such attempts include models dependent on non-radiative decay pathways like intersystem crossing, internal conversion, and hydrogen bonding interactions.