Formal Intramolecular (4 + 1)-Cycloaddition of Dialkoxycarbenes: Control of the Stereoselectivity and a Mechanistic Portrait
摘要:
The stereoselective synthesis of 5-5, 6-5, and 7-5 fused O-heterocyclic compounds is reported. The key reaction is a formal intramolecular (4 + 1)-cycloaddition involving a dialkox-ycarbene and an electron-deficient diene where the stereo-selectivity is dependent on the length of the tether. An analysis of the stereochemical outcome of this reaction sheds light on its complex mechanistic picture. High-level calculations were used to support the proposed mechanistic portrait.
Diastereoselective Addition of Prochiral Nucleophilic Alkenes to α-Chiral <i>N</i>-Sulfonyl Imines
作者:David A. Gutierrez、James Fettinger、K. N. Houk、Kaori Ando、Jared T. Shaw
DOI:10.1021/acs.orglett.1c04219
日期:2022.2.11
to chiral α-alkoxy N-tosyl imines is described. Alkene geometry is selectively transferred to the newly formed carbon–carbon bond, resulting in stereochemicalcontrol of C1, C2, and C3 of the resulting 2-alkoxy-3-N-tosyl-4-alkyl-5-hexene products. A computational analysis to elucidate the high selectivity is also presented. This methodology was employed in the synthesis of two naturally occurring isomers
interested in the straightforward method for the synthesis of 1,1-difluoro- 1,3-butadienes from the cross-couplingreaction of 2,2-diflu-oroalkenylmetal reagent with alkenylhalides, which should be a simple and efficient method. Palladium-catalyzed cross- coupling reactions of 1,1-difluorohomoallenyl bromide with aryl bromides and iodides and arylboronicacids provided the corresponding 1,1-difluoro-1,3-butadienes
Total Synthesis of Pyrrolidine and Piperidine Natural Products via TMSOTf-Mediated “5/6-<i>endo-dig</i>” Reductive Hydroamination of Enynyl Amines
作者:Santosh J. Gharpure、Raj K. Patel、Krishna S. Gupta
DOI:10.1021/acs.orglett.3c02115
日期:2023.8.11
acid-mediated 5/6-endo-dig reductive hydroamination cascade of enynyl amines. The brevity of the developed strategy allowed for the collective stereoselective totalsynthesis of various alkaloids, including (±)-pyrrolidine cis-225H, (±)-epi-197B, (±)-epi-225C, the family of (+)-solenopsins and (+)-isosolenopsins, and the formal synthesis of (±)-bgugaine and (+)-azimic acid.
A series of Ala and Aoc analogues of (-)-ternatin were prepared, and their bioactivities were assessed by a fat-accumulation inhibition assay using 3T3-L1 adipocytes, which led to the discovery of key structure-activity relationships (SAR).