Lessons in Strain and Stability: Enantioselective Synthesis of (+)-[5]-Ladderanoic Acid
The synthesis of structurally complex and highly strained natural products provides unique challenges and unexpected opportunities for the development of new reactions and strategies. Herein, the synthesis of (+)-[5]-ladderanoic acid is reported. En route to the target, unusual and unexpected strain release driven transformations were uncovered. This occurrence required a drastic revision of the synthetic design that ultimately led to the development of a novel stepwise cyclobutane assembly by an allylboration/Zweifel olefination sequence.
Hancock, Erin N.,Kuker, Erin L.,Tantillo, Dean J.,Brown, M. Kevin
supporting information
p. 436 - 441
(2019/11/25)
Organo-Cation Catalyzed Asymmetric Homo/Heterodialkylation of Bisoxindoles: Construction of Vicinal All-Carbon Quaternary Stereocenters and Total Synthesis of (-)-Chimonanthidine
A novel chiral spirocyclic amide (SPA)-derived triazolium organocatalyst has been designed and demonstrated to effect asymmetric homo- and heterodialkylations of various bisoxindoles, enabling enantioselective construction of vicinal all-carbon quaternary stereocenters. These reactions feature excellent enantio- and diastereoselectivities (up to 99% ee and >20:1 dr) as well as good to high yields (up to 89% over two steps). As an application of this methodology, the first asymmetric total synthesis of (-)-chimonanthidine has been achieved.
A series of alkyl-substituted pyrethroid analogs were synthesized from ethyl 3,3-dialkyl-3'-alkylspiro-2-carboxylates.Cyclopropanation of acetyl- and methoxycarbonylbenzofluvenes, obtained from 1H-indene, by sulfur ylides containing a fragment of the pyrethroid alcohol component, led to compounds not exhibiting insecticidal activity.
Tolstikov, G. A.,Galin, F. Z.,Ignatyuk, V. K.,Lakeev, S. N.,Berg, A. A.,et al.
p. 1090 - 1100
(2007/10/02)
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