Reactivity of Halodiazoacetates and Halodiazoamides

The work in this thesis is divided into four parts: 1. The study and development of a novel synthesis of 2,5-dioxopyrrolidin-1-yl 2-diazoacetate, a much desired building block (BB) for synthesis of diazo-esters and -amides. The existing literature procedure gave low yields. Hence, a new synthesis for making the BB was developed based on a coupling reaction of a carboxylic acid and N-hydroxysuccinimide (NHS). The reaction was optimized by investigating reaction conditions like solvent, base, concentrations, reaction temperature, reaction time and coupling reagents. The developed method gave better yield than the existing literature procedure. The scope and limitation of BB as a reagent for synthesizing diazo-amides and -esters was investigated by synthesizing a series of diazoamides and a diazoester. 2. Investigation of the thermal stability of a series of halo diazo-esters and -amides. Halo diazo-esters and amides have low thermal stability and their thermal decomposition rates have been investigated with a method based on IR spectroscopy. Significant differences in thermal stability of secondary and tertiary diazo-amides and -esters was uncovered. 3. A DFT-study of the singlet-triplet gap and the barriers towards release of N2 (g) from the diazo compound to produce the corresponding carbenes. DFT calculations were carried out to compliment the experimental results. The height of the calculated transition barriers correlated with the measured half-lives. Differences in the triplet-singlet gap for diazo-esters and -amides were uncovered. 4. A brief exploration and investigation of a few selected test reactions. The reactivity of the halo diazo-amides and -esters were briefly studied in a few selected cyclopropanation and C-H insertion reactions under catalytic conditions. Among the test reactions was rhodium catalyzed cyclopropanation of styrene, uncovering differences in the diasteromeric ratio of the cyclopropane product of Br-2,2,2-trifluoroethyl 2-diazoacetate (TFEDA) and Br-2,2,2-trichloroethyl 2-diazoacetate (TCEFA) compared to Br-ethyl diazoacetate (EDA). In test reactions with halo diazoamides no cyclopropanation or C-H insertion products were found. The products that were found in all the test reactions had gone through the same type of reaction.