Transition metal catalyzed reactions are indispensable tools for the asymmetric construction of carbon–carbon bonds. Traditionally, cross-coupling reactions have relied on the use of aryl, vinyl or 1o alkyl electrophiles. Advances in asymmetric catalysis have permitted the use of 2o alkyl electrophiles in cross-coupling reactions allowing for the development of several stereoconvergent transformations. Herein, we report a complementary approach to asymmetric cross-coupling reactions by means of the development of stereospecific, nickel-catalyzed transformations of benzylic alcohol derivatives.

Our initial efforts were directed toward expanding upon a Kumada cross-coupling reaction of secondary benzylic ethers with methylmagnesium iodide previously reported by the Jarvo laboratory. We extended the scope of this reaction by developing conditions to enable the use of aryl Grignard reagents for the construction of enantioenriched triarylmethanes by stereospecific nickel-catalyzed cross-coupling of diaryl methanol derivatives. The reaction proceeds in high enantiospecificity and overall inversion. This methodology is used to prepare a single enantiomer of an anti-breast-cancer agent.

Further advances in our cross-coupling methodology are demonstrated in the development of a stereospecific Suzuki–Miyaura coupling of benzylic carbamates and pivolates with aryl- and heteroarylboronic esters. The reaction proceeds with selective inversion or retention at the electrophilic carbon depending on the nature of the ligand. Tricyclohexylphosphine ligand provides product with retention, while an NHC ligand provides product with inversion. The reaction proceeds in high enantiospecificity to afford either enantiomer of a variety of triarylmethanes.

Taking advantage of our growing expertise in nickel catalyzed reactions of secondary alkyl electrophiles, we designed the first alkyl Heck reaction with control of stereochemistry at the electrophilic carbon. Enantioenriched methylenecyclopentanes are synthesized by stereospecific, nickel-catalyzed Heck cyclizations of secondary benzylic ethers. The reaction proceeds in high yield and enantiospecificity for benzylic ethers of both π-extended and simple arenes. Ethers with pendant 1,2-disubstituted olefins form trisubstituted olefins with control of both absolute configuration and alkene geometry. The diastereoselective synthesis of a polycyclic furan is demonstrated.

In the final chapter of this work, we demonstrate a nickel-catalyzed generation of secondary benzylzinc reagents from 2-pyridyl carbinols that are phosphorylated in situ. A variety of benzylzinc reagents are formed in high yield, allowing for facile hydrogenolysis of 2-pyridyl carbinols. The utility of this transformation is highlighted in a high-yielding intramolecular addition of a secondary benzylzinc reagent to an α,β-unsaturated ester.

This dissertation addresses the methodology used in classifying speech rhythms in order to resolve a long-standing linguistic conundrum about whether languages differ rhythmically. There is a widespread perception, both among linguists and the general population, that some languages are stress-timed and others are syllable timed. Stress-timed languages are described as having less-regular rhythms, as syllable durations vary according to the placement of stress in the phrase. Meanwhile, syllable-timed languages are described as displaying less variation in rhythm, which syllable durations being more regular. This dissertation quantitatively evaluates these described rhythmic differences in Spanish,Portuguese, and English. The first chapter introduces speech rhythms and reviews past literature on their perception and production. The second chapter evaluates a widely used metric of speech rhythms, the PVI, and determines that it is not effective in distinguishing between two dialects of Spanish. The third chapter compares the speech rhythms of Mexican and Chicano Spanish. This chapter concludes that Chicano Spanish is more restricted in its vowel duration variability, while Mexican Spanish employs both highly variable durations (i.e. stress-timed) and highly uniform durations (i.e. syllable-timed). The fourth chapter describes a perception study used to compare the speech rhythms of Spanish, English, and Portuguese, and shows that these languages' rhythms do not always group according to language. In the fifth chapter, I describe a study of the production of the same utterances initially used in the perception experiment; this allows an analysis of what prompts the perceptual differences in speech rhythm described in Chapter Four. The sixth and final chapter discusses the implications and applications of these findings and gives direction for further investigation. Although both production and perception studies of speech rhythms have been performed in the past, my dissertation expands these methodologies by combining production and perception data is a single analysis. I use perception data to relatively classify the rhythms of utterances through low-pass speech filtering, then analyze the production of these data computationally to provide a more complete perspective of what prompts differences in speech-rhythms and how Spanish, Portuguese, and English data relate rhythmically. Thus, my dissertation is thorough, while still addressing traditional rhythm metrics and employing current computational methodology. It seeks to challenge linguists' methodologies in quantitatively addressing speech rhythms, and to further clarify the position of Spanish, Portuguese, and English on the speech rhythm continuum.