Classical Reagents: New Surprises in Palladium-Catalyzed CC Coupling Reactions

Stereocomplementary and Parallel Syntheses of Multi-Substituted (E)-, (Z)-Stereodefined α,β-Unsaturated Esters: Application to Drug Syntheses

Ubiquitous α,β-unsaturated esters are well recognized as key structural olefin scaffolds in organic chemistry. (E)- and (Z)-steroselectivity is the most critical issue in their synthesis, however, (E)- and (Z)- stereocomplementary synthetic methods remain quite limited. The present account discloses general (E)-, (Z)-stereocomplementary syntheses of a variety of α,β-unsaturated esters from highly accessible (E)-, (Z)-stereodefined enol tosylates derived from β-ketoesters and α-formyl esters. Step 1 toward the stereocomplementary preparation of (E)-, (Z)-stereodefined enol tosylates is implemented by using inexpensive reagents under mild reaction conditions. Step 2 toward the highly stereoretentive synthesis of (E)- and (Z)-stereodefined α,β-unsaturated esters involves Suzuki-Miyaura, Negishi, Sonogashira, Iron-catalyzed, Mizoroki-Heck, and Buchwald-Hartwig cross-coupling reactions. Notably, this strategy was successfully applied for parallel drug syntheses of (E)- and (Z)-zimelidine, (E)- and (Z)-tamoxifen, and Merck's cyclopropane pharmacophore. Representative successful utilizations by other groups are also introduced.

Palladium-catalysed Heck-type alkenylation reactions in the synthesis of quinolines. Mechanistic insights and recent applications

Recent developments in Pd(0)- and Pd(ii)-catalysed alkenylation reactions for the synthesis of quinolines focusing on mechanistic understanding.

Palladium-catalysed coupling of α-halo vinylphosphonate and α-phosphonovinyl sulfonate with alkylzincs: straightforward and versatile synthesis of α-alkyl vinylphosphonates

Easy and efficient access to α-alkylated vinylphosphonates via Pd-catalysed Negishi coupling!

Divergent Synthetic Access to E- and Z-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens

A highly substrate‐general synthesis of all‐carbon‐substituted E‐ and Z‐stereodefined olefins is performed. The method comprises two sets of parallel and stereocomplementary preparations of (E)‐ and (Z)‐α,β‐unsaturated esters involving two robust and distinctive reactions: 1) stereocomplementary enol tosylations using readily available TsCl/diamine/(LiCl) base reagents, and 2) stereoretentive Negishi cross‐coupling using the catalysts [Pd(dppe)Cl₂] (for E) and [Pd(dppb)Cl₂] (for Z). The present parallel approach is categorized as both type I (convergent approach: 16 examples, 56–87 % yield) and type II (divergent approach: 18 examples, 70–95 % yield). The obtained (E)‐ and (Z)‐α,β‐unsaturated ester scaffolds are successfully transformed into various E‐ and Z‐stereodefined known and novel olefins (8×2 derivatization arrays). As a demonstration, application to the parallel synthesis of both (E)‐ and (Z)‐tamoxifens, a representative motif of all‐carbon‐substituted olefins, is accomplished in a total of eight steps with an overall yield of 58 % (average 93 %) and 57 % (average 93 %), respectively.

(E)- and (Z)-stereodefined enol phosphonates derived from β-ketoesters: stereocomplementary synthesis of fully-substituted α,β-unsaturated esters

A versatile, robust, and stereocomplementary synthesis of fully-substituted (E)- and (Z)-stereodefined α,β-unsaturated esters 3 from accessible α-substituted β-ketoesters 1via (E)- and (Z)-enol phosphonates was achieved.