Enzymatic halocyclization of allenic alcohols and carboxylates: a biocatalytic entry to functionalized O-heterocycles
作者:J. Naapuri、J. D. Rolfes、J. Keil、C. Manzuna Sapu、J. Deska
DOI:10.1039/c6gc01926a
日期:——
Chloroperoxidase fromCaldariomycesfumago catalyzes the aerobic oxidative halocyclization of allenic alcohols and carboxylates yielding functionalized furan and pyran heterocycles as valuable synthetic scaffolds. Thanks to an oxidase-initiated redox cascade,...
Studies on Electrophilic Reaction of Tertiary 2,3-Allenols with NBS in H<sub>2</sub>O or Aqueous MeCN: An Efficient Selective Synthesis of 2-Bromoallylic Ketones, 1,2-Allenyl Ketones, or 3-Bromo-2,5-dihydrofurans
作者:Jing Li、Wangqing Kong、Yihua Yu、Chunling Fu、Shengming Ma
DOI:10.1021/jo9018717
日期:2009.11.20
Previously, we observed that the electrophilic reaction of 2,3-allenols with X+ (X = Br, I) affords 3-halo-2-alkenals or 2-halo-2-alkenyl ketones in aqueous MeCN (MeCN/H2O = 15:1). However, the reaction of tertiary 2,3-allenols with NBS under these reaction conditions affords a mixture of rearrangement products (aldehydes or ketones) together with 1-bromovinyl epoxides in a low selectivity. Due to
以前,我们观察到2,3-烯醇与X +(X = Br,I)的亲电反应在水性MeCN(MeCN / H 2 O = 15:1)。然而,在这些反应条件下,叔2,3-烯醇与NBS的反应在低选择性下提供了重排产物(醛或酮)与1-溴乙烯基环氧化物的混合物。由于2-卤代烯丙基酮的合成潜力,我们决定进一步探索该反应。筛选后,我们观察到末端叔2,3-烯醇与NBS在水中的亲电反应可通过Br +的顺序亲电相互作用以高达97%的产率高度选择性地提供2-溴代烯丙基酮与丙二烯部分形成可能具有更取代的C═C键的三元溴中间体,然后进行1,2-芳基或1,2-烷基转移以打开应变的三元环并质子消除形成羰基官能团。当R 1和R 2(与羟基连接的碳原子上的取代基)均为烷基时,这两个基团之一迁移;当R 1和R 2都为烷基时,这两个基团之一被迁移。与1,2-丙二烯基环烷醇一起,观察到扩环反应。R 1是芳基,R 1将仅转移形成2-溴烯丙基酮。有趣的是,在用10滴Et
Enzymatic Bromocyclization of α‐ and γ‐Allenols by Chloroperoxidase from
<i>Curvularia inaequalis</i>
作者:Janne M. Naapuri、Philip K. Wagner、Frank Hollmann、Jan Deska
DOI:10.1002/open.202100236
日期:2022.1
Vanadate-dependent chloroperoxidasefromCurvulariainaequalis catalyzes 5-endo-trig bromocyclizations of α-allenols as well as the 5-exo-trig bromocyclizations of γ-allenols to produce valuable halofunctionalized furans. An aqueous biphasic emulsion, based on either cationic or non-ionic surfactants, acts as reaction medium, and allows effective halogenation reactions utilizing hydrogen peroxide as
Arylative Allenol Cyclization via Sequential One‐pot Enzyme & Palladium Catalysis
作者:Janne M. Naapuri、Gustav A. Åberg、Jose M. Palomo、Jan Deska
DOI:10.1002/cctc.202001619
日期:2021.1.20
Suzuki‐type cross coupling enables the direct arylative cyclization of allenic alcohols with boronic acids. This modular approach to unsaturated five‐membered O‐heterocycles proceeds in an aqueous emulsion with air as terminal oxidant. Here, the enzymatic oxidative activation of simple halide salts acts as traceless ring‐closure‐inducing event to trigger the subsequent C−C coupling. With the original protocol