[reaction: see text] Pd[(-)-sparteine]Cl(2) catalyzes the formation of dialkyl acetals from styrene derivatives with Markovnikov regioselectivity. The substrate scope of this reaction has been investigated, and initial mechanistic studies indicate that the reaction proceeds through an enol ether intermediate and a Pd-hydride.

A 2-week hands-on activity is described in which introductory organic chemistry students prepare, obtain, and analyze 1H NMR spectra of known organic compounds to draw conclusions on multiplicity, integration, and chemical shift. Students performed well on instructor-designed worksheets to develop chemical shift correlation graphs based on their findings. While exam scores remain an assessment, this activity includes student-generated videos about 1H NMR spectroscopy as an equitable evaluation of student learning. The videos contained accurate information and allowed students to utilize a familiar approach, the recording devices on their cell phones and computers, to present information. Student responses to this activity were favorable. This is an attractive approach for students that augments knowledge of 1H NMR spectroscopy with traditional lecture and laboratory experiments.

Basic groups from acid hydrolysis: 1,3,5-Triazaadamantanes (TAAs) are shown to degrade in acidic conditions to produce basic by-products. The rate of hydrolysis can be tuned by changing the substituents present on the aromatic rings. TAA containing dendrimers can be synthesized readily as a result of their branched architecture.Keywords controlled degradation; dendrimers; macromolecule synthesis; guest binding Degradable polymers are important constituents of environmentally benign products and are used in applications that range from tissue engineering [1] to gene [2] and drug delivery. [1,3] Hydrolytically labile polymers, such as polyesters, are particularly useful because of the ubiquitous presence of water in the environment and in living organisms. However, polyesters produce acidic byproducts upon degradation, a limitation for a number of applications. [4] Poly-phosphazenes [5] are promising alternatives, but there is a need for new monomers that degrade to benign byproducts. Herein we report the synthesis and study of 1,3,5-triazaadamantane (TAA) as a water-soluble unit for controlled degradation and aldehyde release. Formed from the condensation of a tris(aminomethyl)methane unit and three aromatic aldehydes, [6] the TAA unit hydrolyzes under physiological conditions reverting to its precursors that are basic. We show that the degradation rate of the TAA unit can be tuned with substituents and further synthesize a hydrophilic TAA based dendrimer that is capable of binding solvatochromic probes.The preparation of TAA 2 by the condensation of trisamine 1 and benzaldehyde (Figure 1a) was reported by Woulfe. [6a] In our hands, this procedure produced 2a and 2b in a 9:1 ratio ( 1 H NMR). Difference nuclear Overhauser effect (NOE) studies were performed on 2a to establish the relative spatial orientation of the methine protons (Figure 1b). To confirm further its identity, an X-ray analysis was performed on crystals of 2a grown by the slow evaporation of an acetonitrile solution (Figure 1c). Submitting minor isomer 2b to the reaction conditions resulted in a 9:1 ratio of 2a to 2b, indicating the reaction to be thermodynamically controlled.

Expanding the use of modern characterization methods and discovery-based experiments is a goal for many second-year undergraduate introductory organic chemistry laboratory instructors. Large enrollments for this course limit the number and range of experiments that can be performed due to constraints on instruments and resources. The experiment described employs a discovery-based approach to enhance a previously published mixed-aldol condensation experiment by incorporating modern structure analysis methods.