Chemoenzymatic synthesis of rengyoside -A, -B, isorengyoside and synthesis of their aglycones
摘要:
The chemoenzymatic synthesis of a group of naturally occurring cyclohexylethanoids, rengyoside-A, -B and isorengyoside, has been performed by enzymatic glucosidation of their chemically synthesized aglycones, rengyol, rengyoxide and isorengyol. (C) 1997 Published by Elsevier Science Ltd.
in high to quantitative yields via the 1,5-CH insertion reaction of generated magnesium carbenoid intermediates. When this procedure was commenced with acyclic ketones, multi-substituted tetrahydrofurans were obtained in up to a 96% yield. This procedure provides a new and good way for the synthesis of 1-oxaspiro[4.n]alkanes and tetrahydrofurans with the formation of a carbon–carbon bond between a carbenoid
A novel approach towards the construction of the galanthamine skeleton was demonstrated by the total synthesis of (±)-lycoramine. The key steps include a Pd-catalyzed intramolecular cyclization to form the seven-membered azepane ring and a spontaneous intramolecular Michael addition to afford the five-membered furan ring. This synthetic route has also been demonstrated to be useful for the preparation
A novel approach towards the construction of the galanthamine skeleton was demonstrated by the Pd-catalyzed cyclization of N-[2-(1,4-dioxa-spiro[4,5]dec-7-en-8-yl)-ethyl]-2-iodo-4-methoxy-N-methyl-benzamide (23), with formation of the benzazepine ring and creation of a quaternary carbon.
Grob-Type Fragmentation Releases Paracyclophane Ring Strain in a Late-Stage Precursor of Haouamine A
作者:Liming Cao、Chenbo Wang、Peter Wipf
DOI:10.1021/acs.orglett.9b00424
日期:2019.3.1
A ketene [2 + 2]-addition, an intramolecular aldol reaction, a Suzuki–Miyaura coupling, and a chemoselective lactam reduction were used to prepare a late-stage precursor of haouamine A. Exposure to acid led to a Grob-type fragmentation of the strained 3-aza[7]paracyclophane ring, followed by a tandem Pictet–Spengler reaction of the intermediate iminium ion and conversion to a novel 1,4a-propanocyclopenta[b]pyridine
烯酮[2 + 2]加成,分子内醛醇缩合反应,Suzuki-Miyaura偶联和化学选择性内酰胺还原被用于制备花甲胺A的后期前体。暴露于酸中会导致Grob型碎裂应变后的3-氮杂[7]对环环烷环,随后是中间亚胺离子的串联Pictet-Spengler反应,并转化为新型的1,4a-丙环戊[ b ]吡啶。该级联反应也可能与天然产物的作用机理有关。
Synthesis of 13C-Labeled Possible Intermediates in the Biosynthesis of Phenylethanoid Derivatives, Cornoside and Rengyosides.
In order to clarify the biosynthetic pathway of C6-C2 unit compounds containing salidroside, cornoside, and rengyosides A and B in oleaceous plants, 13C-labeled putative precursors, 4-hydroxyphenylethanol, salidroside and cornoside, were prepared.
为了弄清油料植物中含有水杨苷、玉米须苷、雷公藤苷 A 和 B 的 C6-C2 单元化合物的生物合成途径,制备了 13C 标记的假定前体--4-羟基苯乙醇、水杨苷和玉米须苷。