Optimized methods for the regioselective and stereospecific synthesis of both trisubstituted and tetrasubstituted olefins as single isomers from E-β-chloro-α-iodo-α,β-unsaturated esters have been developed from previous work done in the Ogilvie lab. These optimized methods have led to the synthesis of trans isomeric enediynes that can be photoisomerized to their respective cis isomers and subsequently undergo microwave-assisted Bergman cycloaromatizations. Furthermore, both cis and trans isomeric enediynes that have propargyl ether substituents have been found to be able to undergo photoactivated Bergman cyclizations without the need for an intermolecular hydrogen donor. A mechanism study has confirmed that the Bergman cyclization products that form without the presence of an intermolecular hydrogen donor undergo a series of 1,5-hydrogen shifts as intermediates. A series of optimizations to these reactions were carried out, in part by utilizing electron-donating or electron-withdrawing functional groups to help stabilize the resulting radicals that form on the intermediates, and thus increase the yield of the associated Bergman cyclization products.

Optimized methods for the regioselective and stereospecific synthesis of both trisubstituted and tetrasubstituted olefins as single isomers from E-β-chloro-α-iodo-α,β-unsaturated esters have been developed from previous work done in the Ogilvie lab. These optimized methods have led to the synthesis of trans isomeric enediynes that can be photoisomerized to their respective cis isomers and subsequently undergo microwave-assisted Bergman cycloaromatizations. Furthermore, both cis and trans isomeric enediynes that have propargyl ether substituents have been found to be able to undergo photoactivated Bergman cyclizations without the need for an intermolecular hydrogen donor. A mechanism study has confirmed that the Bergman cyclization products that form without the presence of an intermolecular hydrogen donor undergo a series of 1,5-hydrogen shifts as intermediates. A series of optimizations to these reactions were carried out, in part by utilizing electron-donating or electron-withdrawing functional groups to help stabilize the resulting radicals that form on the intermediates, and thus increase the yield of the associated Bergman cyclization products.

Optimized methods for the regioselective and stereospecific synthesis of both trisubstituted and tetrasubstituted olefins as single isomers from E-β-chloro-α-iodo-α,β-unsaturated esters have been developed from previous work done in the Ogilvie lab. These optimized methods have led to the synthesis of trans isomeric enediynes that can be photoisomerized to their respective cis isomers and subsequently undergo microwave-assisted Bergman cycloaromatizations. Furthermore, both cis and trans isomeric enediynes that have propargyl ether substituents have been found to be able to undergo photoactivated Bergman cyclizations without the need for an intermolecular hydrogen donor. A mechanism study has confirmed that the Bergman cyclization products that form without the presence of an intermolecular hydrogen donor undergo a series of 1,5-hydrogen shifts as intermediates. A series of optimizations to these reactions were carried out, in part by utilizing electron-donating or electron-withdrawing functional groups to help stabilize the resulting radicals that form on the intermediates, and thus increase the yield of the associated Bergman cyclization products.

Optimized methods for the regioselective and stereospecific synthesis of both trisubstituted and tetrasubstituted olefins as single isomers from E-β-chloro-α-iodo-α,β-unsaturated esters have been developed from previous work done in the Ogilvie lab. These optimized methods have led to the synthesis of trans isomeric enediynes that can be photoisomerized to their respective cis isomers and subsequently undergo microwave-assisted Bergman cycloaromatizations. Furthermore, both cis and trans isomeric enediynes that have propargyl ether substituents have been found to be able to undergo photoactivated Bergman cyclizations without the need for an intermolecular hydrogen donor. A mechanism study has confirmed that the Bergman cyclization products that form without the presence of an intermolecular hydrogen donor undergo a series of 1,5-hydrogen shifts as intermediates. A series of optimizations to these reactions were carried out, in part by utilizing electron-donating or electron-withdrawing functional groups to help stabilize the resulting radicals that form on the intermediates, and thus increase the yield of the associated Bergman cyclization products.

Part A: Synthesis of 5- and 6-Membered Camphor-Based Hydrazides as Organocatalysts for Cycloaddition Reactions The favorable environmental and reactivity qualities of organocatalysts are contributing to the popularization of this method for the acceleration of enantioselective reactions. Research in our group has been focused on the synthesis of camphor-derived hydrazide based organocatalysts for enantioselective cycloaddition processes. Recent results suggest that the presence of an exocyclic electron withdrawing group on the hydrazide moiety, as well as the incorporation of the hydrazide moiety into a 6-membered ring, may have a beneficial effect on the kinetics of the catalysts. A variety of camphor-based cyclic hydrazides have been synthesized and tested in Diels-Alder reactions, varying both the ring size and placement of the electron withdrawing group. Part B: Synthesis of Isocampholenic Acids by the Rearrangement of Camphor Derivatives A variety of substituted isocampholenic acid derivatives have been prepared by rearrangement of the camphor skeleton of a variety of tertiary alcohols derived from ketopinic acid. The reaction is highly reliable and retains the stereochemical information from the camphor scaffold. This rearrangement represents an efficient way to prepare synthetically useful isocampholenic acids. Mechanistic experiments show that the rearrangement does not involve exogenous water and that a short-lived carbocation is implicated in the reaction. Part C: Diastereoselective Formation of Quaternary Centers from Stereodefined Trisubstituted Alkenes Previous work in our laboratory has focused on the preparation of single-isomer tri- and tetra-substituted olefins. This methodology has been used in the construction of a variety of alkenyl esters in good to excellent yields. These alkenyl esters could then be transformed into the corresponding 3,3-disubstituted allyl boronates in a stereocontrolled fashion. There are a limited number of methods available to prepare single isomer 3,3-disubstituted allyl boronates, which can be important precursors in the stereoselective preparation of all-carbon quaternary centers. Our methodology has therefore been applied to the construction of single isomer 3,3-disubstituted allyl boronates and subsequently used in the stereoselective generation of all-carbon quaternary centers by the reaction of these allyl boronates with aldehydes.