A convergent stereoselective route to the C16-C37 fragment of sorangicin A is disclosed using an α-chloro sulfide for C-C bond formation. The key intermediate, an α,β-unsaturated ketone, is revealed by a [2,3] sigmatropic rearrangement of a propargylic sulfoxide. Three disparate approaches are detailed to create the C25 carbinol stereocenter. The -2,6-disubstitution of the THP ring is secured by ionic hydrogenation. A cross-metathesis reaction and Julia-Kocienski olefination furnish the C16-C37 fragment of sorangicin A.
We report a copper-catalyzed regio-, diastereo-, and enantioselective allylic alkylation of allyl bromides using 1,1-diborylalkanes as prochiral nucleophiles. This methodology employs copper(I) bromide as a catalyst, an ()-BINOL-derived phosphoramidite as a ligand, and lithium benzoate as a crucial additive. The reaction affords enantioenriched homoallylic boronic esters possessing vicinal stereocenters in good yields and high diastereo- and enantioselectivity.
A critical step in the development of a convergent synthesis of an MRGPRX2 antagonist () was the S2 reaction with a highly functionalized lactamide electrophile and a unique difluoropiperidine nucleophile containing a pyridine -oxide moiety. Initial reactions with sulfonate leaving groups exhibited superb stereoselectivity, but yields were very low due to side reactions originated from competitive Kornblum reactions of the pyridine -oxide and the sulfonates. Markedly improved reaction profiles were achieved by including stoichiometric lithium triflate.
Axially chiral allenes bearing organoboron groups are highly sought-after building blocks in organic synthesis due to their potential for generating a wide range of axially and centrally chiral molecules. However, the existing methods for preparing axially chiral allenes containing boron group are primarily limited to the synthesis of allenyl boronic esters, and strategies for accessing axially chiral homoallenyl boronic esters are still scarce. Here, we report the general method for synthesizing axially chiral α-boryl-homoallenyl boronic esters through a highly regio- and stereoselective copper-mediated S2'-addition of newly prepared (diborylalkyl)copper species to chiral propargyl electrophiles.
Breast cancer metastasis leads to worse outcomes and higher mortality rates, with CTSL playing a key role in promoting this process by breaking down the extracellular matrix.
Research showed that CTSL is more expressed in breast tumor tissues and links to processes like the epithelial-mesenchymal transition.
The study found that SnuCalCpI15, an inhibitor from a plant, effectively slows down CTSL activity, reduces breast cancer cell migration and invasion, suggesting its potential as a new treatment to combat metastasis.
We report the stereoselective total synthesis of rhodocoranes I and J in 10 steps and 16.4% overall yield from ()-limonene. The synthesis was accomplished through the convergent assembly of a highly substituted chiral cyclopentanone and a lithiated furanyl silyl ketene acetal.
