Synthesis of α,α'-trans-oxepanes through an organocatalytic oxa-conjugate addition reaction

Stereoselective Entry into α,α'-C-Oxepane Scaffolds through a Chalcogen Bonding Catalyzed Strain-Release C-Septanosylation Strategy

The utility of unconventional noncovalent interactions (NCIs) such as chalcogen bonding has lately emerged as a robust platform to access synthetically difficult glycosides stereoselectively. Herein, we disclose the versatility of a phosphonochalcogenide (PCH) catalyst to facilitate access into the challenging, but biologically interesting 7-membered ring α,α'-C-disubstituted oxepane core through an α-selective strain-release C-glycosylation. Methodically, this strategy represents a switch from more common but entropically less desired macrocyclizations to a thermodynamically favored ring-expansion approach. In light of the general lack of stereoselective methods to access C-septanosides, a remarkable palette of silyl-based nucleophiles can be reliably employed in our method. This include a broad variety of useful synthons, such as easily available silyl-allyl, silyl-enol ether, silyl-ketene acetal, vinylogous silyl-ketene acetal, silyl-alkyne and silylazide reagents. Mechanistic investigations suggest that a mechanistic shift towards an intramolecular aglycone transposition involving a pentacoordinate silicon intermediate is likely responsible in steering the stereoselectivity.

Iron- and Organo-Catalyzed Borrowing Hydrogen for the Stereoselective Construction of Tetrahydropyrans

Stereocontrolled oxa-Michael additions are challenging, given the high reversibility of the process, which ultimately leads to racemization of the newly formed stereocenters. When iron-catalyzed borrowing hydrogen from allylic alcohols was combined with a stereocontrolled organocatalytic oxa-Michael addition, a wide array of chiral tetrahydropyrans were efficiently prepared. The reaction could be performed in a diastereoselective manner from pre-existing stereocenters or enantioselectively from achiral substrates. The key to success was the reactivity of the iron complex, which was selective for allylic alcohol dehydrogenation and irreversibly led the reaction to the final product.

Design and organocatalytic synthesis of spirooxindole–cyclopentene–isoxazole hybrids as novel MDM2–p53 inhibitors

An organocatalytic 1,6-cycloaddition with exclusive α-regioselectivity to synthesize designed spirooxindole–cyclopentene–isoxazole hybrids as novel MDM2–p53 inhibitors.

Computational exploration of Fe55@C240-catalyzed Fischer–Tropsch synthesis

DFT calculations showed possible hydrocarbon chain growth on Fe55@C240 preferentially via a CO insertion mechanism.

Advances in the synthesis of glycosidic macrolides: clavosolides A-D and cyanolide A

Covering: 2005 to 2016Clavosolides A-D and cyanolide A are glycosidic macrolides and represent a new family of marine natural products. They possess a number of unusual structural features and have attracted considerable interest from the synthetic community. This review presents a comprehensive survey of all aspects of the clavosolides A-D and cyanolide A. Specific topics include isolation, structure determination, biological activity, and synthetic approaches.

Four-component α-bromo-β-phosphoalkoxylation of aromatic α,β-unsaturated carbonyl compounds

Novel α-bromo-β-phosphoalkoxylated carbonyl compounds were produced in moderate to excellent yields via highly selective four-component reaction involving NBS, a cyclic ether, an organic phosphate and an aromatic α,β-unsaturated carbonyl compound.

Four-component reaction leading to highly functionalized sulfoalkoxy carbonyl compounds

Four components together: a new paradigm of four component reaction brings α-bromo-β-sulfoalkoxyl carbonyl compounds with good stereocontrol in moderate to excellent yields.

Indium triflate-catalyzed stereoselective tandem intramolecular conjugate addition of secondary amines to α,β-bisenones

We report an indium triflate-catalyzed stereoselective intramolecular tandem conjugate addition of secondary amines to α,β-bisenones to afford a 1,2,3-trisubstituted six-membered ring bearing diketone substituents in good to excellent yields at room temperature.