0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content. Variation 4: With Carbon Nucleophiles

DOI: 10.1055/sos-SD-027-00519

Yamane, M.; Narasaka, K.Science of Synthesis, (200427629.

Nucleophilic addition to oxime derivatives with organometals is somewhat difficult because oximes are often less electrophilic and less easily activated than the corresponding imines, due to the conjugation of the O-electron pair to the C=N π-bond. General problems are, in addition to proton abstraction at the α-position, the existence of mixtures of E/Z-isomers, poor electrophilic reactivity of the oxime, and the lability of the ON bond. Accordingly, modification of the organometallic reagents is required in order to decrease their basicity, e.g. combination of alkyllithiums with boron trifluoridediethyl ether complex. O-Alkylformaldehyde oxime has been used to introduce aminomethyl groups to organometals.[‌380‌‌383‌] Organolithium reagents add to α-alkoxyimino carboxylic acid derivatives, which provides a direct method for the synthesis of N-hydroxy-α-amino acids. α-Aminomethylation of esters and amides is achieved by the reaction of their lithium or magnesium enolates with O-alkylaldoximes.[‌380‌] By the reactions with lithium enolates of esters, N-alkoxy-β-lactams 47 can be obtained via cyclization of the resulting α-aminomethylated esters (Scheme 33). β-N-Hydroxyamino acid derivatives are obtained by the reactions of silyl ketene acetals with aldoximes in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate.[‌380‌]

Meeeee 88 Meeeeeeeeee ee β-Meeeeee eee Meeeeeee ee Meeee Meeeeeee ee Meeeee[‌888‌]

Meeeeeeeeee eeee ee eeeeeeeeeeeeee 88 eee eeeeee eeeeeeee eee eee eeeeeeeeeee ee M-(eeeeeeeee)eeeeeeeeeeeeee 88 eeee eeeeee 88 (Meeeee 88).[‌888‌,‌888‌] Meeeeeeeee eeeeeeeee ee eeeeee[‌888‌] ee eeeeeeee eee eeeeeeeeeeeeeeeeee eeeeeeee ee eeeeeeeeeeeeee eeeeeeee ee eeeeee eeeeeeeee.[‌888‌‌888‌]

Meeeee 88 Meeeeeee ee ee Meeeeeeeeeeee ee ee Meeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

M-[8-(8,8-Meeeeeeeeeeeeee)eee-8-ee-8-ee]eeeeeeeeeeeee (88); Meeeeee Meeeeeeee:[‌888‌]

M eeee ee 8,8-eeeeeeeeeeeeeeeeeeeee (88; 8.88e, 88eeee) eee 8-eeeee-8,8,8-eeeeeeeeeeeee (88; 8.88e, 88eeee) ee MMe8 (MMMMMMM: eeeee) (88eM) eee eeeeeeee eee 8e. Meeee eeeeeeee ee Me8M (888eM) eee 8M ee MMe (888eM), eee eee eeeeee eeee eeeeeeeee. Mee eeeeeee eeeee eee eeeeee eeee Me8M (8×88eM). Mee eeeeeee eeeee eee eeeeeeee ee eM88 ee eee eeeeeeee ee 8M ee MMM eeeee eeeeeee, eee eee eeeeeeeee eeee Me8M (8×88eM). Mee eeeeeeee eeee eeeee (MeMM8/M8MM8), eee eeeeeeeeeeeee eeee eee eeeee eeeeeeeeeeeee 88 ee ee eeee eeeeee; eeeee: 8.88e (88%). Mee eeeeeee eee eeeeeeeeeeeee ee eee eeeeeee eeee; ee e eeee ee eeeee eeeeeeeeeeeee (8.88e, 88eeee) ee Me8M (88eM) eee eeeee e eeee ee eeeeee eeee (8.8e, 88eeee) ee MeMM (8eM). Meeee 8e eee eeee eee eeeeeeeeeeee. Mee eeeeeee eee eeeee ee ee MMMe8 (88eM) eee eee eeee eee eeeeeeee. Meee eeeeeeee ee eeeeeeeee eeeee (ee 8888°M; 888eM) eee ee e eeeeeeeeeee eeeee eee eeeeeeeee eee eeeeeeeeeeeeee ee eeee eee eeeeeeeeeeeee eeeeeee ee eeeeeeeee eeeeeeee; eeeee: 8.88e (88%); ee 888.8888°M.