Direct Electrophilic (Benzenesulfonyl)Difluoromethylthiolation with a Shelf‐Stable Reagent

The (benzenesulfonyl)difluoromethylsulfanyl (PhSO₂CF₂S) group is a valuable substituent with specific properties which can provide access to new applications of fluoroalkylthiolated compounds. Direct introduction of this moiety can be performed by in an electrophilic manner by using a new shelf‐stable reagent, namely a (benzenesulfonyl)difluoromethanesulfenamide. Furthermore, mild magnesium‐mediated reduction of the PhSO₂CF₂S group leads to a facile synthesis of difluoromethylthiolated molecules and their deuterated analogs.     

Well‐Defined CuC2F5 Complexes and Pentafluoroethylation of Acid Chlorides

Four new well‐defined Cu^I complexes bearing a C₂F₅ ligand have been prepared and fully characterized: [(Ph₃P)₂CuC₂F₅] ( 2 ), [(bpy)CuC₂F₅] ( 3 ), [(Ph₃P)Cu(phen)C₂F₅] ( 4 ), and [(IPr*)CuC₂F₅] ( 5 ). X‐ray structures of all four have been determined, showing that the C₂F₅‐ligated Cu atom can be di‐ ( 5 ), tri‐ ( 2 and 3 ), and tetracoordinate ( 4 ). The mixed phen‐PPh₃ complex 4 is a highly efficient fluoroalkylating agent for a broad variety of acid chlorides. This high‐yielding transformation represents the first general method for the synthesis of RCOC₂F₅ from the corresponding RCOCl.     

Hypervalent Pentafluoroethylgermanium Compounds, [(C2F5)nGeX5−n]− and [(C2F5)3GeF3]2− (X=F,Cl; n=2–5)

This paper gives an account on hypervalent fluoro‐ and chloro(pentafluoroethyl)germanium compounds. The selective synthesis of the tris(pentafluoroethyl)dichlorogermanate salt [PNP][(C₂F₅)₃GeCl₂] as well as its X‐ray structural analysis is described. As a representative example for pentafluoroethylfluorogermanates, the synthesis and structure of 2,4,6‐triphenylpyryliumtris(pentafluoroethyl)difluorogermanate [C₂₃H₁₇O][(C₂F₅)₃GeF₂] is reported. Fluoride‐ion affinities for pentafluoroethylgermanes were calculated using quantum chemical methods, disclosing (C₂F₅)₃GeF as a weaker Lewis acid than (C₂F₅)₃SiF or (C₂F₅)₃PF₂. The theoretical results were confirmed by experiments and give the basis of a synthetic protocol for (C₂F₅)₃GeF. Pentakis(pentafluoroethyl)germanate [PPh₄][Ge(C₂F₅)₅] was detected as an intermediate during the synthesis of [PPh₄][(C₂F₅)₄GeF] starting from tris(pentafluoroethyl)difluorogermanate and LiC₂F₅.     

N‐Trifluoromethylthiosaccharin: An Easily Accessible,Shelf‐Stable,Broadly Applicable Trifluoromethylthiolating Reagent

A new, electrophilic trifluoromethylthiolating reagent, N‐trifluoromethylthiosaccharin, was developed and can be synthesized in two steps from saccharin within 30 minutes. N‐trifluoromethylthiosaccharin is a powerful trifluoromethylthiolating reagent and allows the trifluoromethylthiolation of a variety of nucleophiles such as alcohols, amines, thiols, electron‐rich arenes, aldehydes, ketones, acyclic β‐ketoesters, and alkynes under mild reaction conditions.     

(E)‐,(Z)‐Parallel Preparative Methods for Stereodefined β,β‐Diaryl‐ and α,β‐Diaryl‐α,β‐unsaturated Esters: Application to the Stereocomplementary Concise Synthesis of Zimelidine

Parallel and practical methods for the preparation of both (E)‐ and (Z)‐β‐aryl¹‐β‐aryl²‐α,β‐unsaturated esters 1 and (E)‐ and (Z)‐α‐aryl¹‐β‐aryl²‐α,β‐unsaturated esters 2 are described. These methods involve accessible, robust, stereocomplementary N‐methylimidazole (NMI)‐mediated enol tosylations (14 examples, 70–99 % yield), as well as stereoretentive Suzuki–Miyaura cross‐couplings (36 examples, 64–99 % yield). The highlighted feature of the present protocol is the use of parallel and stereocomplementary approaches to obtain highly (E)‐ and (Z)‐pure products 1 and 2 by utilizing sequential enol tosylations and cross‐coupling reactions. An expeditious and parallel synthesis of (E)‐ and (Z)‐zimelidine ( 3 ), which is a highly representative selective serotonin reuptake inhibitor (SSRI), was performed by utilizing the present methods.     

β,β‐Diborylated Subporphyrinato Boron(III) Complexes as Useful Synthetic Precursors

Iridium‐catalyzed borylation of B‐aryl meso‐free subporphyrinato boron(III) complexes (hereinafter referred to simply as subporphyrins) with bis(pinacolato)diboron gave 2,13‐diborylated subporphyrins regioselectively, which served as promising synthetic precursors for 2,13‐diarylated subporphyrins and doubly β‐to‐β 1,3‐butadiyne‐bridged subporphyrin dimers. 2,13‐Diarylated subporphyrins display perturbed absorption spectra, depending upon the β‐aryl substituents. Doubly 1,3‐butadiyne‐bridged syn and anti subporphyrin dimers thus prepared exhibit differently altered absorption spectra with split Soret‐like bands, which have been accounted for in terms of exciton coupling.     

Synthesis of α,α‐Difluoromethylene Alkynes by Palladium‐Catalyzed gem‐Difluoropropargylation of Aryl and Alkenyl Boron Reagents

gem‐Difluoropropargyl bromides are versatile intermediates in organic synthesis, but have rarely been employed in transition‐metal‐catalyzed cross‐coupling reactions. The first palladium‐catalyzed gem‐difluoropropargylation of organoboron reagents with gem‐difluoropropargyl bromides is now reported. The reaction proceeds under mild reaction conditions with high regioselectivity; it features a broad substrate scope and excellent functional‐group compatibility and thus provides an attractive approach for the synthesis of complex fluorinated molecules, in particular for drug discovery and development.     

PhSO2SCF2H: A Shelf‐Stable,Easily Scalable Reagent for Radical Difluoromethylthiolation

A new shelf‐stable and easily scalable difluoromethylthiolating reagent S‐(difluoromethyl) benzenesulfonothioate (PhSO₂SCF₂H) was developed. PhSO₂SCF₂H is a powerful reagent for radical difluoromethylthiolation of aryl and alkyl boronic acids, decarboxylative difluoromethylthiolation of aliphatic acids, and a phenylsulfonyl‐difluoromethylthio difunctionalization of alkenes under mild reaction conditions.     

Stereocontrolled Synthesis of (E)-β,γ-Unsaturated Esters via Palladium-Catalyzed Cross-Coupling of (E)-Alkenylboronic Acids with α-Bromoacetic Esters

The cross-coupling reaction of trans-alkenylboronic acids with a-bromoacetic esters was firstly studied. It was found that using Pd(OAc)2 as catalyst, a bulky electron-rich phospine, (2-dicyclohexylphospino-biphenyl) as ligand, the reaction can be readily accomplished to give specific (E)-b,g-unsaturated esters in high yields.     

S‐((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon‐Selective Electrophilic Difluoromethylation of β‐Ketoesters, β‐Diketones,and Dicyanoalkylidenes

S‐((Phenylsulfonyl)difluoromethyl)thiophenium salts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiophenium salts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF₂H group to sp³‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (phenylsulfonyl)difluoromethyl group can be readily transformed into CF₂H under mild reaction conditions. Enantioselective electrophilic difluoromethylation was also achieved in the presence of bis(cinchona) alkaloids.     

一种经(E)-α-碘代烯基砜的钯催化交叉偶联反应立体选择合成(1Z,3E)-2-芳砜基取代的1,3-二烯的新方法

（E）-α-Stannylvinyl phenyl（or p-tolyl）sulfones underwent an iododestannylation reaction to afford （E）-α-iodovinyl phenyl（or p-tolyl）sulfones 1, which reacted with （E）-alkenylzirconium（IV） complexes 2 produced in situ by hydrozirconation of terminal alkynes in the presence of a Pd（PPh3）4 catalyst to afford stereoselectively （1Z,3E）-2- phenyl（or p-tolyl）sulfonyl-substituted 1,3-dienes 3 in good yields.     

Nickel‐Catalyzed Difluoromethylation of Arylboronic Acids with Bromodifluoromethane

Although bromodifluoromethane (BrCF₂H) is a simple and readily available fluorine source, direct formation of difluoromethylated arenes with BrCF₂H has not been reported. Herein, we describe an efficient method to access difluoromethylated arenes through a nickel‐catalyzed difluoromethylation of arylboronic acids with BrCF₂H. The reaction exhibits high efficiency, good functional group tolerance and broad substrate scope, thus providing an efficient route for applications in drug discovery and development. Preliminary mechanistic studies reveal that a difluoromethyl radical is involved in the reaction.     

Synthesis and Photophysical Properties of Doubly β‐to‐β Bridged Cyclic ZnII Porphyrin Arrays

A series of doubly β‐to‐β bridged cyclic Zn^II porphyrin arrays were prepared by a stepwise Suzuki–Miyaura coupling reaction of borylated Zn^II porphyrin with different bridge groups. The coupling of the building block of β,β′‐diboryl Zn^II porphyrin 1 with different bridges provided the doubly β‐to‐β carbazole‐bridged Zn^II porphyrin array 3 , the fluorene‐bridged Zn^II porphyrin array 5 , the fluorenone‐bridged Zn^II porphyrin array 7 , and the three‐carbazole‐bridged Zn^II porphyrin ring 8 . The structural assignment of 3 was confirmed by the X‐ray diffraction analysis, which revealed a highly symmetrical and remarkably bent syn‐form structure. The incorporation of bridge units with different electronic effects results in different photophysical properties of the cyclic Zn^II porphyrin arrays. Comprehensive photophysical studies demonstrate that the electron‐withdrawing bridge fluorenone has the largest electronic interaction with the Zn^II porphyrin unit among the series, thus resulting in the highest two‐photon absorption cross‐section values (σ⁽²⁾) of 6570±60 GM for 7 . The present work provides a new strategy for developing porphyrin‐based optical materials.