<p>This thesis describes the use of 2<i>H</i>-azirines, three-membered unsaturatednitrogen-containing heterocycles, as reactive intermediates ina number of Lewis acid promoted alkylations and Diels-Alderreactions providing synthetically useful aziridines.</p><p>In order to carry out this investigation a new generalprocedure for the ring closure of vinyl azides, forming theresultant 3-substituted-2<i>H</i>-azirines, was developed applying low boiling solventsin closed reaction vessels at elevated temperatures.</p><p>The addition of organolithium reagents in the presence ofcommercially available chiral ligands, to the 3-(2-naphthyl)-2<i>H</i>-azirine was studied, which gave the correspondingaziridines.</p><p>Several Lewis acids were shown to catalyze the normalelectron-demand Diels-Alder reaction between 3-alkyl-,3-aromatic-, and 3-ester-substituted 2<i>H</i>-azirines and various dienes. These reactions gave theexpected cycloadducts in moderate yields.</p><p>Using a chiral auxiliary high diastereoselectivity wasobtained in the addition of alkyl radicals to a8-phenylmenthyl-substituted 2<i>H</i>-azirine-3-carboxylate. The alkyl radicals weregenerated from the corresponding trialkyl borane and molecularoxygen. Hydroborations and transmetallations were used toprepare these trialkylboranes. Catalytic amounts of CuClincreased the diastereoselectivity in the radical additionreactions.</p><p>Attempts were made to explain how the coordination of aLewis acid to the azirine nitrogen atom affects thereactivity/stability of the azirine. DFT calculations and NMRexperiments involving Lewis acid-azirine complexes wereperformed.</p><p><b>Keywords:</b>Enantioselective, diastereoselective, vinylazide, 2<i>H</i>-azirines, aziridines, Lewis acid, chiral ligand,chiral auxiliary, organolithiums, Diels-Alder reaction, alkylradicals, triethylborane.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:kth-3822 |
| Date | January 2004 |
| Creators | Risberg, Erik |
| Publisher | KTH, Chemistry, Stockholm : Kemi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Trita-IOK, 1100-7974 ; 2004:92 |
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