Nickel-Catalyzed Decarboxylative Alkenylation of Anhydrides with Vinyl Triflates or Halides
作者:Hui Chen、Shuhao Sun、Xuebin Liao
DOI:10.1021/acs.orglett.9b01048
日期:2019.5.17
Decarboxylative cross-coupling of aliphatic acid anhydrides with vinyl triflates or halides was accomplished via nickel catalysis. This methodology works well with a broad array of substrates and features abundant functional group tolerance. Notably, our approach addresses the issue of safe and environmental installation of methyl or ethyl group into molecular scaffolds. The method possesses high chemoselectivity
The syntheses of four macrocyclic sperminealkaloids, (±)-budmunchiamine A – C (1a – c) and (±)-budmunchiamine L4 (1), were accomplished by Michael addition of spermine to the α,β-unsaturated esters 3a – d, followed by cyclization of the resulting α,ω-tetraamino esters 4a – d with triethoxyantimony; N-methylation of the amino lactams 6a – c yielded the budmunchiamines A – C (1a – c).
四种大环精胺生物碱 (±)-budmunchiamine A – C (1a – c) 和 (±)-budmunchiamine L4 (1) 的合成是通过 Michael 将精胺添加到 α,β-不饱和酯 3a – d 中完成的,然后用三乙氧基锑环化所得的 α,ω-四氨基酯 4a-d;氨基内酰胺 6a – c 的 N-甲基化产生 budmunchiamines A – C (1a – c)。
Synthesis of New Trans Double-Bond Sphingolipid Analogues: Δ<sup>4,6</sup> and Δ<sup>6</sup> Ceramides
Unsaturation was introduced at Delta(4.6) and Delta(6) of the sphingoid chain of naturally occurring ceramide 1 via a beta-keto sulfoxide (12) and sulfone (18) derived from N-Boe-L-serine methyl ester acetonide (9), affording two novel ceramide analogues, (2S,3R)-2-octanoylamidooetadeca-(4E,6E)-diene-1,3-diol (2) and (2S,3R)-2-octanoylamidooetadec-(6E)-ene-1,3-diol (3). After C-alkylation of 12 with (E)1-bromo-2-tetradecene (8), a trans double bond was installed by elimination of PhS(O)H, providing conjugated dienone oxazolidine 13. Reaction of 18 with 8, followed by desulfonation (AI(Hg)), afforded keto-oxazolidine 20, which bears a (E)-Delta(6) double bond. The syntheses of analogues 2 and 3 from ketones 13 and 20, respectively, were completed by the following sequence of reactions: diastereoselective reduction (NaBH4/CeCl3 or DIBAL-H), hydrolysis of the oxazolidine ring, liberation of the amino group, and installation of the N-amide group.