Metal-Free Difunctionalization of Alkynes with 2‑Chlorodithiane for Synthesis of β‑Ketodithianes

Dithianes are versatile umpolung intermediates in organic synthesis but have rarely been employed in radical cross-coupling reactions. Here we describe the oxidative coupling method for alkyne difunctionalization under metal-catalyst-free conditions. The efficient protocol directly affords a variety of β-ketodithianes in good to excellent yields with high regioselectivities. It provides a general pathway for accessing valuable dithianes with controlled formation of a new C–C bond and a C–O bond via a radical coupling pathway

Крос-культурне спілкування на заняттях з ділової англійської мови

The abstract explores cross-cultural communication in Business English classroom as central in preparing students for their successful functioning in business environment. It can be incorporated in BE course through case studies, role-playing, simulations and culture awareness projects.В тезах розглядається крос-культурне спілкування на заняттях з ділової англійської мови як важлива передумова для успішного функціонування студентів у діловому оточенні. В курсі англійської мови цей підхід може бути реалізований за допомогою методу конкретних ситуацій, рольових ігор та проектів

Enantioselective Total Synthesis of (−)-Walsucochin B

The first enantioselective total synthesis of the structurally unique nortriterpenoid (−)-walsucochin B has been accomplished through the cationic polyolefin cyclization initiated by chiral epoxide. The core framework and the stereocenters in the natural product were all constructed in this step. A site-selective, late-stage free-radical halogenation and Seyferth–Gilbert homologation was adopted to install the acetylene moiety to synthesize the phenylacetylene. The absolute configuration of walsucochin B was confirmed through enantioselective total synthesis

N‑Heterocyclic Carbene-Catalyzed Formal [3+2] Annulation of Alkynyl Aldehydes with Nitrosobenzenes: A Highly Regioselective Umpolung Strategy

N-Heterocyclic carbene-catalyzed formal [3+2] annulation of alkynyl aldehydes and nitrosobenzenes has been reported. This transformation provided the novel C–X bond formation under mild conditions in moderate to satisfactory yields. The catalytic protocol allows for a rapid construction of 2,5-disubstituted isoxazol-3­(2H)-ones and 2,3-disubstituted isoxazol-5­(2H)-ones from the same materials via a highly regioselectively umpolung stratgy

N‑Heterocyclic Carbene-Catalyzed Formal [3+2] Annulation of Alkynyl Aldehydes with Nitrosobenzenes: A Highly Regioselective Umpolung Strategy

N-Heterocyclic carbene-catalyzed formal [3+2] annulation of alkynyl aldehydes and nitrosobenzenes has been reported. This transformation provided the novel C–X bond formation under mild conditions in moderate to satisfactory yields. The catalytic protocol allows for a rapid construction of 2,5-disubstituted isoxazol-3­(2H)-ones and 2,3-disubstituted isoxazol-5­(2H)-ones from the same materials via a highly regioselectively umpolung stratgy

Asymmetric Total Synthesis of (−)-Lycospidine A

The first asymmetric total synthesis of the structurally unique <i>Lycopodium</i> alkaloid (−)-lycospidine A, containing an unprecedented five-membered ring, has been accomplished in only 10 steps with 21.6% overall yield from the known conveniently available sulfoxide. This protecting-group-free short synthesis relied on the use of a key amidation/aza-Prins domino cyclization reaction to rapidly construct the tricyclic skeleton and two continuous stereocenters (one of which is a bridged quaternary stereocenter). An intramolecular aldol condensation was successfully utilized to establish the unique five-membered ring, and a late-stage oxidation inspired by biosynthesis pathway was adopted to synthesize the diosphenol ring of (−)-lycospidine A

Concise Formal Synthesis of (+)-Neopeltolide

A concise formal synthesis of (+)-neopeltolide (<b>1</b>) has been accomplished. The synthesis demonstrated high atom efficiency employing only one step of functional group protection. Key steps involved iridium-catalyzed double asymmetric carbonyl allylation, palladium-catalyzed intramolecular alkoxycarbonylation, ruthenium-catalyzed olefin isomerization, and ring-closing metathesis

Synthesis of the Tetracyclic Core (ABCE Rings) of Daphenylline

A concise synthesis of the tetracyclic core (ABCE rings) of daphenylline has been accomplished involving a benzobicyclo[3.3.1] lactam as the key intermediate. This bridged bicyclic intermediate was efficiently constructed via a Brønsted acid promoted intramolecular Friedel–Crafts type Michael addition of a δ-benzyl α,β-unsaturated δ-lactam

Asymmetric Total Synthesis of Cladosporin and Isocladosporin

The first asymmetric total syntheses of cladosporin and isocladosporin were accomplished in 8 steps with 8% overall yield and 10 steps with 26% overall yield, respectively. The relative configuration of isocladosporin was determined via this total synthesis

Bioinspired Collective Syntheses of Iboga-Type Indole Alkaloids

We present the application of a bioinspired collective synthesis strategy in the total syntheses of seven iboga-type indole alkaloids: (±)-tabertinggine, (±)-ibogamine, (±)-ibogaine, (±)-ibogaine hydroxyindolenine, (±)-3-oxoibogaine hydroxyindolenine, (±)-iboluteine, and (±)-ervaoffines D. In particular, tabertinggine and its congeners serve as iboga precursors for the subsequent biomimetic transformations into other iboga-type alkaloids