Regioselective Pd-Catalyzed Synthesis and Application of 3-Methyl-5-bromo-2-pyrone toward Keto-phomactin A
摘要:
An efficient one-step synthetic protocol for 3-methyl-5-bromo-2-pyrone was developed using the C3-selective Pd-catalyzed coupling reaction of 3,5-dibromo-2-pyrone with Me3Al-dimethylaminoethanol complex. A subsequent seven-step reaction sequence provided a cyclohexenyl bromide, which served as the key intermediate for the synthesis of the keto analogue of phomactin A, in 31% overall yield.
描述了一种新颖的核糖型环己烯基核苷类的直接方法。电子需求的Diels-Alder反应形成了所选合成途径的关键步骤。尽管差异很小,但使用NMR进行的构象分析表明,该核苷类似物优先采用2 H 3构象(S型),而“脱氧”环己烯基类似物优先选择C3'内构象(N型)。构象平衡的分析表明,在给定的实验条件下,腺苷与其环己烯基同源物之间的差异在于它们的不同ΔG价值观 此外,在腺苷中,构象偏好是焓起源的,而在环己烯基同源物中,构象偏好是熵的起源的。
TMPZnCl·LiCl to afford zincated heterocycles, which reacted with typical electrophiles. A second magnesiation at position C3 of the 2-pyrone scaffold was achieved by using TMPMgCl·LiCl. Also, the zincation of the 4-pyrone scaffold at position C2 is reported, leading to functionalized 4-pyrones. A regioselective magnesiation of the 2-pyrone scaffold was developed. Magnesiation of this heterocycle by using
Regioselective Synthesis of Substituted Carbazoles, Bicarbazoles, and Clausine C
作者:Gary L. Points、Christopher M. Beaudry
DOI:10.1021/acs.orglett.1c02449
日期:2021.9.3
Substituted carbazoles are efficiently constructed from 3-triflato-2-pyrones and alkynyl anilines. Multiple substituents are tolerated on the carbazole, and complete control of regiochemistry is observed. Complicated and sterically congested substitution patterns are produced. This strategy is also used to prepare substituted bicarbazoles and related biaryls. Finally, the method was showcased in a
取代咔唑由 3-triflato-2-pyrones 和炔基苯胺有效构建。咔唑上可耐受多个取代基,并观察到对区域化学的完全控制。产生了复杂且空间拥挤的替代模式。该策略也用于制备取代的联咔唑和相关联芳基。最后,该方法在咔唑天然产物 clausine C 的合成中得到展示。
H-Bonding Mediated Asymmetric Intramolecular Diels–Alder Reaction in the Formal Synthesis of (+)-Aplykurodinone-1
作者:Joon-Ho Lee、Cheon-Gyu Cho
DOI:10.1021/acs.orglett.8b03250
日期:2018.11.16
stereochemical control element governing the π-facial selectivity of intramolecularDiels–Alder (IMDA) reaction of an enone tethered 2-pyrone. In the IMDA process, the configuration at a stereogenic, hydroxyl bearing an α-carbon in the enone dienophile is conveyed in a highly effective manner through intramolecular hydrogen bonding with the enone carbonyl oxygen. The tricyclic lactone, generated in this process
Divergent Asymmetric Total Synthesis of (+)-Vincadifformine, (−)-Quebrachamine, (+)-Aspidospermidine, (−)-Aspidospermine, (−)-Pyrifolidine, and Related Natural Products
作者:Nengzhong Wang、Shuo Du、Dong Li、Xuefeng Jiang
DOI:10.1021/acs.orglett.7b01292
日期:2017.6.16
uniformly strategic total synthesis of Aspidosperma alkaloids (+)-vincadifformine, (−)-quebrachamine, (+)-aspidospermidine, (−)-aspidospermine, (−)-pyrifolidine, and nine others from efficiently constructed tricyclic ketone 13 is reported. Highlights of these divergent and practical syntheses include (i) stereoselective intermolecular [4 + 2] cycloaddition to establish a C–E ring with one all-carbon quaternary
Tandem or Sequential Coupling−IMDA Cycloaddition Approach to Highly Fused Polycarbocycles
作者:Soo-Jin Pang、Soo-Hyun Min、Haiwon Lee、Cheon-Gyu Cho
DOI:10.1021/jo035354y
日期:2003.12.1
benzotetracycles via a tandem or sequential Pd-catalyzed coupling-intramolecular Diels-Alder (IMDA) cycloaddition. The resulting polycarbocycles can be readily converted into a bicyclo[3.3.1]nonane system upon ozonolysis of the internal double bond.