Pd/Cu‐Catalyzed Enantioselective Sequential Heck/Sonogashira Coupling: Asymmetric Synthesis of Oxindoles Containing Trifluoromethylated Quaternary Stereogenic Centers

An asymmetric palladium and copper co‐catalyzed Heck/Sonogashira reaction between o‐iodoacrylanilides and terminal alkynes to synthesize chiral oxindoles was developed. In particular, a wide range of CF₃‐substituted o‐iodoacrylanilides reacted with terminal alkynes, affording the corresponding chiral oxindoles containing trifluoromethylated quaternary stereogenic centers in high yields with excellent enantioselectivities (94–98 % ee). This asymmetric Heck/Sonogashira reaction provides a general approach to access oxindole derivatives containing quaternary stereogenic centers including CF₃‐substituted ones.     

Diamine‐Catalyzed Addition of ZnEt2 to PhC(O)CF3: Two Mechanisms and Autocatalytic Asymmetric Enhancement

NMR spectroscopic studies of the catalytic addition reaction of ZnEt₂ to PhC(O)CF₃ in the presence of three very efficient catalysts [TMEDA, tBuBOX, and L ; where L is a chiral diamine synthesized from optically pure (R,R)‐1,2‐diphenylethylenediamine and (S)‐2,2′‐bis‐(bromomethyl)‐1,1′‐binaphthalene] reveal large differences in their behavior. For the ligands TMEDA and tBuBOX, the catalysis shows no unusual features and proceeds via [(N?N)Zn(Et){OC(CF₃)(Et)Ph}]. For N?N? L , the observation of autocatalytic asymmetric enhancement during the catalysis, and unusual inverse concentration dependence on the reaction rate, indicate the participation of an additional novel catalytic cycle that goes through a dinuclear intermediate containing one ZnEt₂ and one ZnEt fragment connected by N?N and OR bridges. Interestingly, the ¹⁹F NMR signals of the main product of the reaction ([Zn(Et){OC*(CF₃)(Et)Ph}]₂) allowed us to assess the enantioselectivity of the processes in situ without the assistance of chiral chromatography.     

Conformation of Peptides Containing a Chiral α‐Ethylated α,α‐Disubstituted α‐Amino Acid: (S)‐α‐Ethylleucine (=(2S)‐2‐Amino‐2‐ethyl‐4‐methylpentanoic Acid) within Sequences of Dimethylglycine and Diethylglycine Residues

An optically active (S)‐α‐ethylleucine ((S)‐αEtLeu) as a chiral α‐ethylated α,α‐disubstituted α‐amino acid was synthesized by means of a chiral acetal auxiliary of (R,R)‐cyclohexane‐1,2‐diol. The chiral α‐ethylated α,α‐disubstituted amino acid (S)‐αEtLeu was introduced into the peptides constructed from 2‐aminoisobutyric acid (=dimethylglycine, Aib), and also into the peptide prepared from diethylglycine (Deg). The X‐ray crystallographic analysis revealed that both right‐handed (P) and left‐handed (M) 3₁₀‐helical structures exist in the solid state of CF₃CO‐(Aib)₂‐[(S)‐αEtLeu]‐(Aib)₂‐OEt ( 14 ) and CF₃CO‐[(S)‐αEtLeu]‐(Deg)₄‐OEt ( 18 ), respectively. The IR, CD, and ¹H‐NMR spectra indicated that the dominant conformation of pentapeptides 14 and CF₃CO‐[(S)‐αEtLeu]‐(Aib)₄‐OEt ( 16 ) in solution is a 3₁₀‐helical structure, and that of 18 in solution is a planar C₅ conformation. The conformation of peptides was also studied by molecular‐mechanics calculations.     

Asymmetric Conjugate Addition of Unmodified Cyclic Ketones to Nitroolefins Using Aminophosphonate as the Organocatalyst

本文设计合成了光学纯吡咯烷基磷酸酯,并成功地应用于酮类底物与b-硝基芳基乙烯衍生物的不对称催化Michael加成反应中。在20 mol %催化剂用量下,以10 mol %三氟乙酸作为添加物,无溶剂条件下,0 oC反应7-24小时,Michael加成产物的收率最高达96%,非对映选择性最高可达97:3,ee值最高可达90%。     

Stereoselective Access to Fluorinated and Non‐fluorinated Quaternary Piperidines: Synthesis of Pipecolic Acid and Iminosugar Derivatives

The preparation of optically pure quaternary piperidines, both fluorinated and non‐fluorinated, has been achieved from a chiral imino lactone derived from (R)‐phenylglycinol. In the case of the fluorinated derivatives, the addition of (trifluoromethyl)trimethylsilane (TMSCF₃) followed by iodoamination and migration of the CF₃ group allowed access to four derivatives of α‐(trifluoromethyl)pipecolic acid. A theoretical study of the CF₃‐group rearrangement has been carried out to help establish the reaction mechanism of this uncommon transformation. Moreover, a route to trifluoromethyl‐substituted iminosugars was also developed through the diastereoselective dihydroxylation of suitable synthetic intermediates. Conversely, alkylation of the starting substrate and subsequent cross‐metathesis and aza‐Michael reactions led to α‐alkyl derivatives of the target compounds.     

Preparation of New Ferrocenylmonophosphine Ligands Containing Two Planar Chiral Ferrocenyl Moieties and Their Use for Palladium‐Catalyzed Asymmetric Hydrosilylation of 1,3‐Dienes

Bis{(R_p)‐2‐[(1S)‐1‐methoxyethyl]ferrocenyl}arylphosphines (S,R_p)‐ 9 (aryl=4‐MeOC₆H₄ ( 9a ), Ph ( 9b ), 4‐CF₃C₆H₄ ( 9c ), 3,5‐(CF₃)₂C₆H₃ ( 9d )), which contain two planar chiral ferrocenyl moieties, were prepared via (R_p)‐1‐bromo‐2‐[(1S)‐1‐methoxyethyl]ferrocene ((S,R_p)‐ 8 ). Asymmetric hydrosilylation of linear 1,3‐dienes such as deca‐1,3‐diene ( 10a ) with trichlorosilane in the presence of a palladium catalyst coordinated with 9d gave allylic silanes of up to 93% ee.     

Synthesis,Isolation, and Trifluoromethylation of Two Isomers of C84‐Based Monometallic Cyanide Clusterfullerenes: Interplay between the Endohedral Cluster and the Exohedral Addends

As an emerging member of endohedral fullerenes, metal cyanide clusterfullerenes (CYCF) are unique in terms of the encapsulation of a monometallic cluster. To date the reported carbon cages of CYCFs are limited to C₈₂ and C₇₆, and little is known about the chemical reactivity of CYCFs. Herein, two isomers of the first C₈₄‐based CYCFs, YCN@C₈₄, were isolated as trifluoromethyl derivatives, including YCN@C₈₄(23)(CF₃)₁₈ and three isomers of YCN@C₈₄(13)(CF₃)₁₆, which are based on a unique chiral C ₂‐C₈₄(13) cage. As a common feature of the CF₃ addition patterns, the YCN@C₈₄(CF₃)_16/18 compounds are stabilized by the formation of isolated C=C bonds and benzenoid rings on the carbon cages. The interplay between the endohedral YCN cluster and the exhohedral CF₃ addends was unveiled according to single‐crystal X‐ray diffraction studies, thus offering new insight into the chemical reactivity of CYCFs.     

Synthesis,Isolation, and Trifluoromethylation of Two Isomers of C84‐Based Monometallic Cyanide Clusterfullerenes: Interplay between the Endohedral Cluster and the Exohedral Addends

As an emerging member of endohedral fullerenes, metal cyanide clusterfullerenes (CYCF) are unique in terms of the encapsulation of a monometallic cluster. To date the reported carbon cages of CYCFs are limited to C₈₂ and C₇₆, and little is known about the chemical reactivity of CYCFs. Herein, two isomers of the first C₈₄‐based CYCFs, YCN@C₈₄, were isolated as trifluoromethyl derivatives, including YCN@C₈₄(23)(CF₃)₁₈ and three isomers of YCN@C₈₄(13)(CF₃)₁₆, which are based on a unique chiral C ₂‐C₈₄(13) cage. As a common feature of the CF₃ addition patterns, the YCN@C₈₄(CF₃)_16/18 compounds are stabilized by the formation of isolated C=C bonds and benzenoid rings on the carbon cages. The interplay between the endohedral YCN cluster and the exhohedral CF₃ addends was unveiled according to single‐crystal X‐ray diffraction studies, thus offering new insight into the chemical reactivity of CYCFs.     

Synthesis and Properties of CF3(OCF3)CH‐Substituted Arenes and Alkenes†

A silver‐mediated oxidative trifluoromethylation of easily accessible α‐trifluoromethyl alcohols with TMSCF₃ was developed to access novel CF₃(OCF₃)CH‐containing compounds. Deprotonation of CF₃(OCF₃)CH‐substituted arenes afforded synthetically useful CF₃O‐substituted gem‐difluoroalkenes. Furthermore, evaluation of the lipophilicities (log P) indicated that CH(OCF₃)CF₃ is more lipophilic than the common fluorinated motifs such as CF₃, OCF₃, and SCF₃, thus rendering the CH(OCF₃)CF₃ motif appealing in drug discovery.     

Efficient Access to Multifunctional Trifluoromethyl Alcohols through Base‐Free Catalytic Asymmetric C−C Bond Formation with Terminal Ynamides

The asymmetric addition of terminal ynamides to trifluoromethyl ketones with a readily available chiral zinc catalyst gives CF₃‐substituted tertiary propargylic alcohols in up to 99 % yield and 96 % ee. The exclusion of organozinc additives and base as well as the general synthetic utility of the products are key features of this reaction. The value of the β‐hydroxy‐β‐trifluoromethyl ynamides is exemplified by selective transformations to chiral Z‐ and E‐enamides, an amide, and N,O‐ketene acetals. The highly regioselective hydration, stereoselective reduction, and hydroacyloxylation reactions proceed with high yields and without erosion of the ee value of the parent β‐hydroxy ynamides.     

Enantioselective Synthesis of Glutarimide Alkaloids Cordiarimides A,B, Crotonimides A,B, and Julocrotine

Five glutarimide alkaloids cordiarimide A ( 5 ), cordiarimide B ( 6 ), crotonimide A ( 3 ), crotonimide B ( 4 ), and julocrotine ( 2 ) have been synthesized starting from Boc‐L‐glutamine ( 7 ). The benzylic alcohol chiral centre of cordiarimides B ( 6 ) has been established in 6:1 diastereoselectivity by catalytic asymmetric hydrogenation using Zhou's catalytic system Pd(CF₃CO₂)₂/(R,R)‐Me‐DuPhos.     

Chiral Fluorinated α‐Sulfonyl Carbanions: Enantioselective Synthesis and Electrophilic Capture,Racemization Dynamics,and Structure

Enantiomerically pure triflones R¹CH(R²)SO₂CF₃ have been synthesized starting from the corresponding chiral alcohols via thiols and trifluoromethylsulfanes. Key steps of the syntheses of the sulfanes are the photochemical trifluoromethylation of the thiols with CF₃Hal (Hal=halide) or substitution of alkoxyphosphinediamines with CF₃SSCF₃. The deprotonation of RCH(Me)SO₂CF₃ (R=CH₂Ph, iHex) with nBuLi with the formation of salts [RC(Me)? SO₂CF₃]Li and their electrophilic capture both occurred with high enantioselectivities. Displacement of the SO₂CF₃ group of (S)‐MeOCH₂C(Me)(CH₂Ph)SO₂CF₃ (95 % ee) by an ethyl group through the reaction with AlEt₃ gave alkane MeOCH₂C(Me)(CH₂Ph)Et of 96 % ee. Racemization of salts [R¹C(R²)SO₂CF₃]Li follows first‐order kinetics and is mainly an enthalpic process with small negative activation entropy as revealed by polarimetry and dynamic NMR (DNMR) spectroscopy. This is in accordance with a C_α? S bond rotation as the rate‐determining step. Lithium α‐(S)‐trifluoromethyl‐ and α‐(S)‐nonafluorobutylsulfonyl carbanion salts have a much higher racemization barrier than the corresponding α‐(S)‐tert‐butylsulfonyl carbanion salts. Whereas [PhCH₂C(Me)SO₂tBu]Li/DMPU (DMPU = dimethylpropylurea) has a half‐life of racemization at ?105 °C of 2.4 h, that of [PhCH₂C(Me)SO₂CF₃]Li at ?78 °C is 30 d. DNMR spectroscopy of amides (PhCH₂)₂NSO₂CF₃ and (PhCH₂)N(Ph)SO₂CF₃ gave N? S rotational barriers that seem to be distinctly higher than those of nonfluorinated sulfonamides. NMR spectroscopy of [PhCH₂C(Ph)SO₂R]M (M=Li, K, NBu₄; R=CF₃, tBu) shows for both salts a confinement of the negative charge mainly to the C_α atom and a significant benzylic stabilization that is weaker in the trifluoromethylsulfonyl carbanion. According to crystal structure analyses, the carbanions of salts {[PhCH₂C(Ph)SO₂CF₃]Li? L }₂ ( L =2 THF, tetramethylethylenediamine (TMEDA)) and [PhCH₂C(Ph)SO₂CF₃]NBu₄ have the typical chiral C_α? S conformation of α‐sulfonyl carbanions, planar C_α atoms, and short C_α? S bonds. Ab initio calculations of [MeC(Ph)SO₂tBu]^? and [MeC(Ph)SO₂CF₃]^? showed for the fluorinated carbanion stronger n_C→σ* and n_O→σ* interactions and a weaker benzylic stabilization. According to natural bond orbital (NBO) calculations of [R¹C(R²)SO₂R]^? (R=tBu, CF₃) the n_C→σ*_{S? R} interaction is much stronger for R=CF₃. Ab initio calculations gave for [MeC(Ph)SO₂tBu]Li ? 2 Me₂O an O,Li,C_α contact ion pair (CIP) and for [MeC(Ph)SO₂CF₃]Li ? 2 Me₂O an O,Li,O CIP. According to cryoscopy, [PhCH₂C(Ph)SO₂CF₃]Li, [iHexC(Me)SO₂CF₃]Li, and [PhCH₂C(Ph)SO₂CF₃]NBu₄ predominantly form monomers in tetrahydrofuran (THF) at ?108 °C. The NMR spectroscopic data of salts [R¹(R²)SO₂R³]Li (R³=tBu, CF₃) indicate that the dominating monomeric CIPs are devoid of C_α? Li bonds.     

Pd/Cu-Catalyzed Enantioselective Sequential Heck/Sonogashira Coupling: Asymmetric Synthesis of Oxindoles Containing Trifluoromethylated Quaternary Stereogenic Centers

An asymmetric palladium and copper co-catalyzed Heck/Sonogashira reaction between o-iodoacrylanilides and terminal alkynes to synthesize chiral oxindoles was developed. In particular, a wide range of CF₃-substituted o-iodoacrylanilides reacted with terminal alkynes, affording the corresponding chiral oxindoles containing trifluoromethylated quaternary stereogenic centers in high yields with excellent enantioselectivities (94–98 % ee). This asymmetric Heck/Sonogashira reaction provides a general approach to access oxindole derivatives containing quaternary stereogenic centers including CF₃-substituted ones.     

Preparation of Enantiomerically Pure Compounds Employing Anodic Oxidations of Carboxylic Acids – A Late Review of Research Done in the 1980ies

There are widely unknown enantiopure building blocks and non‐conventional transformations described in this old work that could become useful in today's diversity‐oriented organic synthesis world. Coupling and mixed couplings of functionalized CF₃‐substituted chiral radicals by Kolbe electrolysis of carboxylic acids lead to hexafluoro‐hexane‐2,5‐diol and to butyro‐ and valerolactone derivatives with functional‐group relationships that normally require components with reactivity umpolung. Oxidative decarboxylation of amino‐acid and peptide derivatives by Hofer‐Moest electrolyses provide entry into the synthetic use of chiral acyliminium‐ion intermediates. Chiral oxazoline and thioazoline building blocks (from serine, threonine, and cysteine) are accessible for substitutions and cycloadditions. The stereochemical course of oxidative CO₂H replacement in serine by nucleophilically introduced groups with retention of configuration is discussed.     

Cu/Pd Synergistic Dual Catalysis: Asymmetric α‐Allylation of an α‐CF3 Amide

Despite the burgeoning demand for fluorine‐containing chemical entities, the construction of CF₃‐containing stereogenic centers has remained elusive. Herein, we report the strategic merger of Cu^I/base‐catalyzed enolization of an α‐CF₃ amide and Pd⁰‐catalyzed allylic alkylation in an enantioselective manner to deliver chiral building blocks bearing a stereogenic carbon center connected to a CF₃, an amide carbonyl, and a manipulable allylic group. The phosphine complexes of Cu^I and Pd⁰ engage in distinct catalytic roles without ligand scrambling to render the dual catalysis operative to achieve asymmetric α‐allylation of the amide. The stereoselective cyclization of the obtained α‐CF₃‐γ,δ‐unsaturated amides to give tetrahydropyran and γ‐lactone‐fused cyclopropane skeletons highlights the synthetic utility of the present catalytic method as a new entry to non‐racemic CF₃‐containing compounds.     

Electrochemical and Chemical Syntheses of Trifluoromethylating Reagents and Trifluoromethyl Substituted Compounds

The electroreduction of the halofluoromethanes CF₃Br, CF₂Br₂ and CF₂BrCl has been studied in high‐pressure stainless steel autoclaves at different cathodes [Pt, steel (V2A, V4A), glassy carbon (GC)] and in various solvent‐supporting electrolyte systems (SSE), e.g. DMF/[Bu₄N]Br, NMP/[Bu₄N]BF₄ etc. The reduction potentials for CF₃Br increase from Pt (–1.6 V) < V2A (–1.8 V) < GC (–2.1 V) and are lower for CF₂Br₂ and CF₂BrCl suggesting a reductive cleavage of C‐X bonds as the first step. CF₂Br₂ and CF₂BrCl show a two‐step reduction in accord with the C–X bond energies (C–F > C–Cl > C–Br) and the “Perfluoro‐effect”. The electrolysis of CF₃Br in different SSE‐systems with sacrificial zinc or cadmium anodes has been reinvestigated with our experimental set‐up to elucidate the influence of the experimental conditions on the type and ratio of the products. The observed products CF₃MBr·42L and (CF₃)₂M·42L (M = Zn, Cd; L = DMF or AN) are the same as in the previous investigations, but are obtained in different ratios, as a rule caused by a parallel chemical corrosion of the respective anodes. By using aluminium as sacrificial anode no CF₃Al compounds are formed. The CF₃ species generated by electroreduction of CF₃Br react with the solvents via hydrogen abstraction and formation of CF₃H. The current yield with respect to the dissolution of the Al anode reaches 120 % indicating a considerable chemical corrosion in addition to the anodic oxidation. This result enabled a one‐pot trifluoromethylation reaction of NMP as organic carbonyl substrate and solvent with CF₃Br and aluminium powder (ratio 3 : 2) at higher temperatures (> 70 °C). The complete reaction of CF₃Br to give CF₃H and 1‐methyl‐2‐trifluoromethyl‐4,5‐dihydropyrrol allowed the isolation of the latter by vacuum condensation and distillation in 45 % yield, rel. to the CF₃Br used. Gallium and indium were also applied as sacrificial anodes in combination with CF₃Br as substrate. In both cases, anodic current yields of about 280 % indicated an extreme chemical corrosion together with cathodic metal depositions corresponding to the cathodic current yield. These deposits – in contrast to those of Zn and Cd – do not react with CF₃Br in Grignard‐type conversions to CF₃Ga and CF₃In compounds. So, the observed products (CF₃)_nMBr_3–n·L (M = Ga, In; n 1‐3; L = DMF, NMP) are obviously formed by chemical corrosion of the electro‐activated anodes. Finally, electrochemical and chemical trifluoromethylations were successfully carried out, using R₃SiCl (R = Me, Vi, Ph), Me₃M′Cl (M′ = Ge, Sn) and aluminium anodes or Al‐powder. The products were characterized either after isolation or in the product solutions by NMR‐spectroscopic investigations.     

A Cinchona Alkaloid‐Functionalized Mesostructured Silica for Construction of Enriched Chiral β‐Trifluoromethyl‐β‐Hydroxy Ketones over An Epoxidation‐Relay Reduction Process

A cinchona alkaloid‐functionalized heterogeneous catalyst is prepared through a thiol‐ene click reaction of chiral N‐(3,5‐ditrifluoromethylbenzyl)quininium bromide and a mesostructured silica, which is obtained by co‐condensation of 1,2‐bis(triethoxysilyl)ethane and 3‐(triethoxysilyl)propane‐1‐thiol. Structural analyses and characterizations disclose its well‐defined chiral single‐site active center, and electron microscopy images reveal its monodisperse property. As a heterogenous catalyst, it enables an efficient asymmetric epoxidation of achiral β‐trifluoromethyl‐β,β‐disubstituted enones, the obtained chiral products can then be converted easily into enriched chiral β‐trifluoromethyl‐β‐hydroxy ketones through a sequential epoxidation‐relay reduction process. Furthermore, such a heterogeneous catalyst can be recovered conveniently and reused in asymmetric epoxidation of 4,4,4‐trifluoro‐1,3‐diphenylbut‐2‐enone, showing an attractive feature in a practical construction of enriched chiral β‐CF₃‐substituted molecules.     

Visible light‐induced controlled radical polymerization of methacrylates with perfluoroalkyl iodide as the initiator in conjugation with a photoredox catalyst fac‐[Ir(ppy)]3

A new visible light‐induced controlled radical polymerization of methacrylate with perfluoro‐1‐iodohexane (CF₃(CF₂)₅I) as the initiator in the presence of a photoredox catalyst (fac‐[Ir(ppy)₃]) was developed. Mechanistically, a photoexcited fac‐[Ir(ppy)₃]* complex reacted with dormant C‐I species to generate the chain propagating radical and Ir^IVI complex, which could be reversibly reduced by the propagating radical. The molecular weight (M_n) and the corresponding distribution index (M_w/M_n = 1.4) were controlled in the polymerization of methyl methacrylate (MMA). For the polymerization of functional monomers, such as glycidyl methacrylate (GMA) and trifluoroethyl methacrylate, their monomer conversions could be up to 96 and 94%, respectively. No polymerization reaction took place without external light stimulation, indicating that the system was an ideal photo “on?off” switchable system. Furthermore, a clean diblock copolymer PMMA‐b‐PGMA was successfully synthesized with PMMA‐I as the macroinitiator. With CF₃(CF₂)₅I as the initiator, short CF₃(CF₂)₅? group tags were introduced on the produced polymer chains. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3283–3291     

Protic NNN and NCN Pincer‐Type Ruthenium Complexes Featuring (Trifluoromethyl)pyrazole Arms: Synthesis and Application to Catalytic Hydrogen Evolution from Formic Acid

NNN and NCN pincer‐type ruthenium(II) complexes featuring two protic pyrazol‐3‐yl arms with a trifluoromethyl (CF₃) group at the 5‐position were synthesized and structurally characterized to evaluate the impact of the substitution on the properties and catalysis. The increased Brønsted acidity by the highly electron‐withdrawing CF₃ pendants was demonstrated by protonation–deprotonation experiments. By contrast, the IR spectra of the carbonyl derivatives as well as the cyclic voltammogram indicated that the electron density of the ruthenium atom is negligibly influenced by the CF₃ group. Catalysis of these complexes in the decomposition of formic acid to dihydrogen and carbon dioxide was also examined. The NNN pincer‐type complex 1 a with the CF₃ group exhibited a higher catalytic activity than the tBu‐substituted analogue 1 b . In addition, the bis(CF₃‐pyrazolato) ammine derivative 4 catalyzed the reaction even in the absence of base additives.     

Chlorination‐Promoted Cage Transformation of IPR C92 Discovered via Trifluoromethylation under Formation of Non‐classical C92(NC)(CF3)22

High‐temperature trifluoromethylation of isolated‐pentagon‐rule (IPR) fullerene C₉₂ chlorination products followed by HPLC separation of C₉₂(CF₃)_n derivatives resulted in the isolation and X‐ray structural characterization of IPR C₉₂(38)(CF₃)₁₈ and non‐classical C₉₂(NC)(CF₃)₂₂. The formation of C₉₂(38)(CF₃)₁₈ as the highest CF₃ derivative of the known isomer C₉₂(38) can be expected. The formation of C₉₂(NC)(CF₃)₂₂ was interpreted as chlorination‐promoted cage transformation of C₉₂(38) followed by trifluoromethylation of non‐classical C₉₂(NC) chloride. Noticeably, C₉₂(NC)(CF₃)₂₂ shows the highest degree of trifluoromethylation among all known CF₃ derivatives of fullerenes. The addition patterns of C₉₂(38)(CF₃)₁₈ and C₉₂(NC)(CF₃)₂₂ are discussed and compared to the chlorination patterns of C₉₂(38)Cl_n compounds.