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Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 160 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988. http://hdl.handle.net/2142/70420 (UMI)AAI8908646 Chemistry, Organic Diastereoselectivity of Organometallic Additions to Nitrones text Coates, Robert M. Chang, Zen-Yu 2014-12-15T23:19:21Z 2014-12-15T23:19:21Z 10000-01-01 1988 1988 The diastereoselectivity of organometallic additions to nitrones bearing stereogenic substituents has been investigated. High and complementary diastereoselectivity was observed in the additions of Grignard reagents to nitrones (e.g. 62) bearing a potentially chelating $\beta$-alkoxy group on nitrogen. The high facial diastereoselectivity is explained by a simple chelation model which was supported(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)by $\sp1$H NMR analysis of a nitrone-magnesium bromide complex (86). However, the opposite selectivity resulted from the reaction of methylmagnesium bromide with the corresponding silyl ether (68). N-Deoxygenation of N,N-dialkylhydroxylamine adducts was achieved by lithium-ammonium reduction of the hydroxylamino carbonates (90 and 95) and phosphates (114). N-Dealkylation by periodic acid cleavage of the resulting amino alcohols (91 and 96) and subsequent hydrolysis of the imine products provided non-racemic chiral amines. The optical purities of the amines were determined by HPLC analyses of their 3,5-dinitrobenzamide derivatives (94 and 97). The relative stereochemistry of selected hydroxylamine adducts was established by N-deoxygenation of the adducts to amines (115), by conversion of the adducts to primary amines, by periodate cleavage of a $\beta$-hydroxyhydroxylamine (118) and by various correlations. Low selectivity was observed in the organometallic additions to C-($\alpha$-alkoxy)nitrones (74-76). Organometallic additions to nitrones (70-71) prepared from carbohydrates were also surveyed but further experiments are necessary to explore the potential for chiral amine syntheses by this approach. Formation of tetrahydrooxadiazine dimers in the reactions of N-benzylidene-N-(1-arylalkyl)nitrones with methyllithium was also observed. Made available in DSpace on 2014-12-15T23:19:21Z (GMT). No. of bitstreams: 1 8908646.pdf: 6204857 bytes, checksum: 1cfe5354d1ec054ccbc6d994822b6165 (MD5) Previous issue date: 1988 Embargo set by: Seth Robbins for item 70586 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.