A facile approach towards synthesis of verbalactone and biologically active δ-lactones using d-glucose

Enantioselective C(sp3)-C(sp3) Reductive Cross-Electrophile Coupling of Unactivated Alkyl Halides with α-Chloroboronates via Dual Nickel/Photoredox Catalysis

Substantial advances in enantioconvergent C(sp³)-C(sp³) bond formations have been made with nickel-catalyzed cross-coupling of racemic alkyl electrophiles with organometallic reagents or nickel-hydride-catalyzed hydrocarbonation of alkenes. Herein, we report an unprecedented enantioselective C(sp³)-C(sp³) reductive cross-coupling by the direct utilization of two different alkyl halides with dual nickel/photoredox catalysis system. This highly selective coupling of racemic α-chloroboronates and unactivated alkyl iodides furnishes chiral secondary alkyl boronic esters, which serve as useful and important intermediates in the realm of organic synthesis and enable a desirable protocol to fast construction of enantioenriched complex molecules.

Ni-Catalyzed Enantioselective Dialkyl Carbinol Synthesis via Decarboxylative Cross-Coupling: Development, Scope, and Applications

The first enantioselective decarboxylative Negishi-type alkylations of α-oxy carboxylic acids are reported via the intermediacy of redox-active esters (RAEs). This transformation enables a radical-based retrosynthesis of seemingly trivial enantiopure dialkyl carbinols. This article includes a discussion of the history of such couplings, the retrosynthetic ramifications of such a coupling, the development of general conditions, and an extensive series of applications that vividly demonstrate how it can simplify synthesis.

α-Pyrone and decalin derivatives from the marine-derived fungus Trichoderma harzianum PSU-MF79

Two new compounds, one α-pyrone (trichoharzianone) and one decalin (trichoharzianin), along with eight known compounds including three decalins, two δ-lactones, two carboxylic acids and one isochroman were isolated from the marine-derived fungus Trichoderma harzianum PSU-MF79. The structures were determined by spectroscopic methods. The relative configuration of trichoharzianin was assigned based on NOEDIFF data and coupling constants whereas the absolute configurations were established by comparison of electronic circular dichroism data with those of the co-metabolites. Known (-)-massoia lactone exhibited mild antifungal activity against Cryptococcus neoformans ATCC90113 flucytosine-resistant, Candida albicans ATCC90028 and C. albicans NCPF3153 with MIC values of 128, 200 and 200 µg/mL, respectively, and weak cytotoxic activity against HCT-116 and MCF-7 cell lines with the respective IC₅₀ values of 17 and 32 µM. In addition, it was noncytotoxic against noncancerous Vero cells with an IC₅₀ value of >100 µM.

Chiral N,N′-dioxide–In(OTf)3-catalyzed asymmetric vinylogous Mukaiyama aldol reactions

The chiralN,N′-dioxide–In(OTf)₃catalyst system has been successfully developed to catalyze the vinylogous Mukaiyama aldol reaction of silyl dienol ester with aldehydes. Furthermore, (R,E)-methyl 5-hydroxydec-2-enoate can be easily converted into (R)-δ-decalactone, (3R,5R)-valerolactone and (4R,6R,10R,12R)-verbalactone.

Structural determination Vitex cymosa Bertero active principle: Diastereoselective synthesis of (+/-)-trans-4-hydroxy-6-propyl-1-oxocyclohexan-2-one and its antinociceptive activity

The diastereoselective synthesis of (+/-)-trans-4-hydroxy-6-propyl-1-oxocyclohexan-2-one, as a mixture trans:cis (3:1), was accomplished using a protocol that combine the Prins cyclization and RuO(4) oxidation. The synthesis this lactone allowed the elucidation of the correct structure of the substance isolated from the barks of Vitex cymosa. The delta-lactones mixture showed significant antinociceptive properties in preliminary tests using the tail flick model assay.