The synthesis of the drugstore beetle pheromone (Stegobinone)

2,3-Dihydro-2,3,5-trimethyl-6-(1-methyl-2-oxobutyl)-4H-pyran-4-one ($\text{1}$ (Stegobinone), the sex pheromone of the drugstore beetle, was successfully prepared from 4,6-dimethyl-3,5,7-nonatrione ($\text{2}$) by a biogenetically plausible scheme.     

Progression of Organic Reactions on Resin Supports Monitored by Single Bead FTIR Microspectroscopy

We report the time courses of five solid-phase reactions obtained using single bead FTIR microspectroscopy. This time-resolved information aided in the determination of the required reaction time, the nature of the solid-phase reaction, and resin property, effectively assisting in the initial phase of our combinatorial chemistry efforts. Our results showed that solid-phase organic reactions proceed faster than generally speculated. In addition, we have shown that reactions on the surface and in the interior of the bead occur at the same rate for reactions studied. The reaction on the TentaGel resin was shown to be not faster than reactions on Wang resin, suggesting that the diffusion of the substrate into polystyrene bead copolymerized with 1% divinylbenzene is not rate-limiting. Finally, the capability of obtaining IR spectra from the partial surface of a single bead demonstrated the femtomolar detection limit of single bead FTIR microspectroscopy.     

Synthesis and evaluation of duocarmycin and CC-1065 analogues incorporating the 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]-3-azaindol-4-one (CBA) alkylation subunit

An efficient eight-step synthesis (53% overall) and the evaluation of 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]-3-azaindol-4-one (CBA) and its derivatives containing an aza variant of the CC-1065/duocarmycin alkylation subunit are detailed. This unique deep-seated aza modification provided an unprecedented 2-aza-4,4-spirocyclopropacyclohexadienone that was characterized chemically and structurally (X-ray). CBA proved structurally identical with CBI, the carbon analogue, including the stereoelectronic alignment of the key cyclopropane, its bond lengths, and the bond length of the diagnostic C3a-N2 bond, reflecting the extent of vinylogous amide (amidine) conjugation. Despite these structural similarities, CBA and its derivatives were found to be much more reactive toward solvolysis and hydrolysis, much less effective DNA alkylating agents (1000-fold), and biologically much less potent (100- to 1000-fold) than the corresponding CBI derivatives.     

A general,highly stereoselective synthesis of amines

The stereochemical course of cycloalkanone imine reductions by a variety of boron hydride reagents is described; very high stereoselectivity with substituted alkali metal borohydrides is reported.     

Molecular composites in thermosets

The synthesis of molecular composites where rigid polymer molecules are reinforcing elements in a thermoset bisimide matrix has been investigated. The approach has been designed to avoid phase separation by selecting systems where reaction of amine-terminated rigid and semiflexible oligomers with maleimide unsaturation occurs prior to crosslinking of the thermoset. This objective has been met for some compositions. The concentration and molecular weight of the rigid oligomers have been varied. The structure of the reinforcing polymer, the reactivity of the maleimide and the conditions for composite synthesis are variables of critical importance, and further work must determine the promise and limitations of this approach.     

Conformational analysis—II: A lanthanide-induced shift nmr and theoretical study of bicyclo [3.1.0] hexan-3-one and adamantanone

The solution conformation of bicyclo [3.1.0] hexan-3-one has been obtained by the use of the shifts induced in its ¹H and ¹³C NMR by Yb(fod)₃. Refinement of the angle of pucker, ∝, of the 5-membered ring indicates that the molecule adopts a flattened boat conformation with ∝ = 195°. This prediction is supported by ab initio, STO-3G, calculations on the isolated molecule. Use of a two- or four-site model for lanthanide-substrate complexing adequately reproduces the experimental data whereas a one-site binding model is unsatisfactory. The importance of multi-site binding is further emphasised by results for the C_2v-symmetric ketone, adamantanone, where only a four-site model gives satisfactory agreement between observed and calculated lanthanide-induced shifts.     

The formation of propylene fumarate oligomers for use in bioerodible bone cement composites

Poly(propylene fumarate) (PPF) oligomers were synthesized by step polymerization using bis(2-hydroxypropyl fumarate) or propylene bis(hydrogen maleate) as starting materials. Oligomers possessing identical degrees of polymerization (DP), but varying in their end group character (either hydroxyl or carboxyl) were first prepared and characterized, then used as part of a bone cement preparation consisting of oligomer, tricalcium phosphate, calcium carbonate, and methyl methacrylate. Compressive strength of the resulting composite appeared to be dependent on both the degree of polymerization of the PPF, and the nature of the oligomers' end groups.