Beilstein J. Org. Chem.2018,14, 2853–2860, doi:10.3762/bjoc.14.264
-bromo-α-hydroxyiminocarboxylate and various alkylfuranes.
Keywords: α-amino ester; α-hydroxyiminoester; [2 + 4] cycloadditions; [2 + 3] cycloadditions; Knoevenagel; nitrosoacrylate; Suzuki–Miyaura; Introduction
Our current work on the chemistry of imidazo[1,2-a]pyrazin-3(7H)-one luciferins [1] has
% overall yield via α-hydroxyiminoester 9, but it also forced us to use borohydrides to avoid the furan ring hydrogenation. Accordingly, an extensive study of the reduction of compound 6ae with borohydrides was made. Trials included reactions run at 0 °C overnight, the use of wet ethanol or dry THF, the
-ylmethylene)propanebis(thioate), the bisthioester homolog of compound 6ae [5]. Finally, the oximation of the pure malonate 3ae only led to a 64% yield of the corresponding α-hydroxyiminoester 2ae, thus accounting for the 33% overall yield reported in Table 1 when we proceeded without purification. It is only
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Graphical Abstract
Scheme 1:
Malonate-based retrosynthesis of α-amino esters.