?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F9753%2F&rft.title=Mechanism+and+Chirality+Transfer+in+Cyclizations+of+Amides+and+Related+Compounds&rft.creator=Guthrie%2C+David+B.&rft.description=The+role+of+halogens+in+the+5-endo-trig+cyclizations+of+radicals+derived+from+N-cyclohexenyl-%CE%B1-haloacetamides+on+the+product+distribution+has+been+thoroughly+investigated.+Under+reductive+radical+conditions%2C+%CE%B1-chloroamides+produce+octahydroindolones%2C+while+%CE%B1-iodoamides+primarily+give+a+mixture+of+hexahydroindolones+and+N-cyclohexenylacetamides.+Kinetic+studies+showed+the+rate+constants+of+cyclization+are+not+critically+halogen-dependent%2C+but+the+ratio+of+cyclized+to+oxidized+products+is+dependent+on+the+halogen+used+in+the+radical+precursor.+When+the+starting+halide+is+easily+reducible%2C+a+single+electron+transfer+from+cyclized+intermediates+to+starting+material+overrides+the+normal+reductive+chain+process.+This+process+spurs+an+ionic%2C+acid-driven+reductive+halogenation+process%2C+which+disrupts+the+anticipated+radical+chain+mechanism.+Addition+of+excess+base+suppresses+the+reductive+dehalogenation+pathway.%3Cbr%3E%3Cbr%3EEnantioenriched+derivatives+of+N-allyl-o-iodoarylcarbamates+undergo+radical+cyclizations+to+give+enantioenriched+dihydroindoles+in+87-100%25+yields+and+83-92%25+chirality+transfers.+Anionic+cyclizations+of+these+substrates+proceed+in+58-74%25+yields+and+84-99%25+chirality+transfers.+N-Aryl+barriers+to+rotation+were+measured+and+found+to+be+comparable+to+similar+o-iodoacetanilides.+The+radical+and+anionic+cyclizations+proceed+with+the+same+sense+of+chirality.%3Cbr%3E%3Cbr%3ERadical+cyclizations+of+N-cyclohexenyl-o-iodoanilides+may+only+occur+through+the+syn+atropisomer+when+an+additional+ortho+substituent+is+present+on+the+aromatic+ring.+When+a+second+ortho+substituent+is+not+present%2C+N-aryl+rotation+of+the+intermediate+radical+is+faster+than+all+competing+processes.+Heck+cyclizations+on+these+substrates+proceed+through+the+anti+atropisomer%2C+requiring+simultaneous+N-aryl+and+N-cyclohexenyl+rotations+to+achieve+the+necessary+transition+state.+The+%CE%B2-elimination+step+of+these+Heck+reactions+occurs+with+complete+syn+selectivity.%3Cbr%3E%3Cbr%3ERadical+cyclizations+of+axially+chiral+%CE%B1-haloacetanilides+which+contain+an+ortho-radical+acceptor+produce+dihydroquinolin-2-ones+in+high+yields+and+with+high+levels+of+chirality+transfer+(80-100%25).+A+model+of+chirality+transfer+has+been+determined+by+absolute+configuration+determination+of+a+substrate+%2F+product+pair+by+X-ray+crystallography.+Secondary+%CE%B1-haloamides+faithfully+cyclize+with+exclusive+trans+selectivity.+This+methodology+has+been+applied+to+a+tandem+6-exo-trig%2F5-exo-trig+radical+cyclization%2C+which+proceeds+with+good+diastereo-+and+enantioselectivity.&rft.date=2009-01-28&rft.type=University+of+Pittsburgh+ETD&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F9753%2F1%2FGuthrieDavidB2008.pdf&rft.identifier=++Guthrie%2C+David+B.++(2009)+Mechanism+and+Chirality+Transfer+in+Cyclizations+of+Amides+and+Related+Compounds.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++