[reaction: see text] A variety of substituted azabicyclo[n.1.0]alkanes were synthesized by intramolecular titanium-mediated cyclopropanation of N-benzyl-N-(2-alkylalk-3-enyl)formamides and N-benzyl-N-alkadienylformamides. N-Benzylpyrroline upon treatment with Grignard reagents undergoes a titanium-mediated carbomagnesiation to yield N-benzyl-N-(2-alkylbut-3-enyl)amines.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/ol027352q | DOI Listing |
J Am Chem Soc
August 2024
Department of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020 Innsbruck, Austria.
The total synthesis of the meroterpenoid ganoapplanin, an inhibitor of T-type voltage-gated calcium channels, is reported. Our synthetic approach is based on the convergent coupling of a readily available aromatic polyketide scaffold with a bicyclic terpenoid fragment. The three contiguous stereocenters of the terpenoid fragment, two of which are quaternary, were constructed by a diastereoselective, titanium-mediated iodolactonization.
View Article and Find Full Text PDFOrg Lett
May 2022
Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
An asymmetric total synthesis of the sarpagine alkaloid (-)-normacusine B is presented. Salient features of this synthesis include a photocatalytic nitrogen-centered radical cascade reaction to assemble the tetrahydrocarbolinone skeleton, a titanium-mediated intramolecular amide-alkene coupling to construct the bridged azabicyclo[3.3.
View Article and Find Full Text PDFOrg Biomol Chem
February 2017
BioLab, Instituto Universitario de Bio-Orgánica "Antonio González" (IUBO-AG), Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna, 38206 La Laguna, Spain.
A total synthesis of (+)-herboxidiene/GEX 1A has been accomplished from (R)- and (S)-lactate esters in a highly efficient manner. Key steps of the synthesis involve substrate-controlled titanium-mediated aldol reactions from chiral lactate-derived ethyl ketones, an oxa-Michael cyclization, an Ireland-Claisen rearrangement, and a Suzuki coupling. Furthermore, computational studies of the oxa-Michael reaction have unveiled the dramatic influence of intramolecular hydrogen bonds on the stereochemical outcome of such cyclizations, whereas biological analyses have clearly proved the important cytoxicity of (+)-herboxidiene/GEX 1A.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2016
Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, NH, 03755, USA.
A convergent coupling reaction is described that enables the stereoselective construction of angularly substituted trans-fused decalins from acyclic precursors. The process builds on our alkoxide-directed titanium-mediated alkyne-alkyne coupling and employs a 1,7-enyne coupling partner. Overall, the reaction is thought to proceed through initial formation of a tetrasusbstituted metallacyclopentadiene, stereoselective intramolecular [4+2] cycloaddition, elimination, isomerization, and regio- and stereoselective protonation.
View Article and Find Full Text PDFJ Am Chem Soc
May 2015
Department of Chemistry, Burke Laboratory, Dartmouth College, Hanover, New Hampshire 03755, United States.
Bridged bicyclic metallacyclopentenes generated from the [4 + 2] cycloaddition of metallacyclopentadienes with alkenes have been proposed as reactive intermediates in the course of [2 + 2 + 2] annulation reactions. Recently a collection of alkoxide-directed Ti-mediated [2 + 2 + 2] annulation reactions have been discovered for the synthesis of densely functionalized hydrindanes, where the bridged bicyclic metallacyclopentenes from intramolecular [4 + 2] were treated as fleeting intermediates en route to cyclohexadiene products formed by formal cheletropic extrusion of Ti(Oi-Pr)2. In studies aimed at understanding the course of these organometallic cascade reactions it was later discovered that these bridged bicyclic intermediates can be trapped by various elimination processes.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!