An efficient and versatile synthesis of cis-hexahydrobenzophenanthridines starting from readily available tetralins has been developed using an intramolecular Friedel-Crafts alkylation as a key step. The substrates were prepared via a highly stereocontrolled rhodium-catalyzed ring-opening reaction of meso-oxabicyclic alkenes and a hydrogenation sequence. Thus, a wide variety of complex tetracyclic compounds have been isolated with a high level of regio-, diastereo-, and enantioselectivity.
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http://dx.doi.org/10.1021/ol2008236 | DOI Listing |
Chemistry
December 2024
Department of Chemistry, University of Kaiserslautern-Landau, Erwin-Schrödinger-Str. 54, 67663, Kaiserslautern, Germany.
A highly stereoselective Brønsted-acid catalyzed synthesis of densely substituted spiroisoindolinones from enamides and 3-hydroxy-isoindolinones is described. With simple Brønsted-acids, such as para-toluene sulfonic acid, spiroisoindolinones with three contiguous stereogenic centers are formed in high yields (up to 97 %) and diastereoselectivities (up to >98 : <2 : 0 : 0 dr) under mild reaction conditions. With the use of a chiral phosphoric acid catalyst, a diastereo- and enantioselective synthesis of the corresponding spiroisoindolinones was achieved.
View Article and Find Full Text PDFChemistryOpen
November 2024
Bio-Organic Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
The major threat to public health due to the outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has been recognised as a global issue. The increase in morbidity is primarily due to the lack of SARS-CoV-2 specific drugs. One of the major strategies to combat this threat is to deactivate the enzymes responsible for the replication of corona virus.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.
In this report, we detail two distinct synthetic approaches to calyciphylline A-type alkaloids himalensine A and daphenylline, which are inspired by our analysis of the structural complexity of these compounds. Using MolComplex, a Python-based web application that we have developed, we quantified the structural complexity of all possible precursors resulting from one-bond retrosynthetic disconnections. This led to the identification of transannular bonds as especially simplifying to the molecular graph, and, based on this analysis, we pursued a total synthesis of himalensine A from macrocyclic intermediates with planned late-stage transannular ring formations.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
State Key Laboratory of Applied Organic Chemistry (SKLAOC), Key Laboratory of Special Function Materials and Structure Design (MOE), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China.
J Org Chem
October 2024
College of Chemistry, International Phosphorus Laboratory, Zhengzhou University, Zhengzhou 450001, China.
New reactions of benzyl phosphine oxide/sulfide with oxalyl chloride are presented. The resulting reactive intermediates, acyl chloride-substituted chlorophosphonium ylides, are capable of undergoing esterification and Friedel-Crafts acylation reactions, ultimately yielding either methyl 2-(2-bromophenyl)-2-(diphenylphosphoryl)acetate or β-carbonyl-diarylphosphine oxide derivatives. Additionally, when an alkynyl group is contained in the acyl chloride-substituted chlorophosphonium ylide, intramolecular cyclization occurs, leading to the formation of a pair of and dichlorophosphonyl benzofulvene isomers.
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