Abstract:A practical method for the formation of thiophosphonates bearing functionalized monocyclic, fused bicyclic and spirocyclic residues is presented. The procedure requires the easily available terminal alkynes as starting materials as well as commercially and readily available reagents such as diethyl thiophosphite. The experimental procedure consists of a one-pot process without any slow addition of one of the reagents.
“…Ar adical addition-cyclization cascadew ith diethyl thiophosphite was initiated at 45 8Cu sing di-tert-butyl hyponitrite (4)a s initiator (Scheme 4b). [23] Interestingly,t his reaction could also be initiated using dicumyl peroxide as photo-initiator.…”
Section: Scheme3a) Decomposition Of Azo Compounds;b)selectede Xamplementioning
confidence: 99%
“…The homolytic cleavage of peroxides has also been achieved at ambient temperature by irradiation with light, for example cumyl peroxide 6 in ar adicala ddition-cyclization cascade like the one shown in Scheme 4b above. [23] Activationb yu ltrasound hasalso been applied, see Scheme 21 below. [30] Alkenyl peroxides 14 are ac lass of highly unstablep eroxides [31] which can be synthesized in situ in order to initiate radical chain reactions, as trategy that avoidsthe dangers connected with storagea nd handling of reactive reagents.…”
Section: Peroxide Initiatorsmentioning
confidence: 99%
“…[2b] Ar adicala ddition-cyclization cascade with thiophosphites was initiated either thermally at 45 8Cw ith azo-initiator 4 (see Scheme 4b above)o ra tr oom temperature using irradiationo f dicumyl peroxide with as un lamp. [23] The thiol-ene reaction shown above (see Scheme 11)w as also efficiently initiated by irradiation with UV light using DMPA( 34)o rasalt of 36 as photoinitiators. [43] 9.…”
An overview of methodsf or the initiation of radical chain reactions by specific initiator compounds, which generate radicals, is given. These can be utilized to initiate any kind of radical chain reactionb yt ransforming substrates into the desired radical intermediates. Azo initiators,p eroxides, nitroxides, trialkylboranes, dialkyl zinc compounds, and type Ip hotoinitiators are discussed, as well as methods of redox-and sonochemical initiation. Methods of direct radical formation from the substrates, such as photoredoxc atalysis or high-energyi rradiation, are not included. The focus of this review lies on rather "low" temperatures in the range of 50 8Cd own to À78 8C, which can be useful to achievem ore selectiver eactions. Illustrative applications of such radical chain initiatorsi navariety of reactions are discussed, including stereoselective ones and polymerizations.Scheme1.Generalmechanism for radical chain reactions transforming substrates (S) into product (P) via intermediate radicals (iR), being initiatedw ith radicals generated from molecularinitiatorsX -Y.Scheme2.Classification of radicalgeneration from initiator molecules X-Y (D:thermal energy;h n:photochemically;)))): sonochemically).Scheme19. Applications of type-I photoinitiators in organics ynthesis.Scheme20. Initiation of athiol-enereaction with N-phenyltriazolinedione 40.Scheme21. Sonochemical initiation of radical reactions.
“…Ar adical addition-cyclization cascadew ith diethyl thiophosphite was initiated at 45 8Cu sing di-tert-butyl hyponitrite (4)a s initiator (Scheme 4b). [23] Interestingly,t his reaction could also be initiated using dicumyl peroxide as photo-initiator.…”
Section: Scheme3a) Decomposition Of Azo Compounds;b)selectede Xamplementioning
confidence: 99%
“…The homolytic cleavage of peroxides has also been achieved at ambient temperature by irradiation with light, for example cumyl peroxide 6 in ar adicala ddition-cyclization cascade like the one shown in Scheme 4b above. [23] Activationb yu ltrasound hasalso been applied, see Scheme 21 below. [30] Alkenyl peroxides 14 are ac lass of highly unstablep eroxides [31] which can be synthesized in situ in order to initiate radical chain reactions, as trategy that avoidsthe dangers connected with storagea nd handling of reactive reagents.…”
Section: Peroxide Initiatorsmentioning
confidence: 99%
“…[2b] Ar adicala ddition-cyclization cascade with thiophosphites was initiated either thermally at 45 8Cw ith azo-initiator 4 (see Scheme 4b above)o ra tr oom temperature using irradiationo f dicumyl peroxide with as un lamp. [23] The thiol-ene reaction shown above (see Scheme 11)w as also efficiently initiated by irradiation with UV light using DMPA( 34)o rasalt of 36 as photoinitiators. [43] 9.…”
An overview of methodsf or the initiation of radical chain reactions by specific initiator compounds, which generate radicals, is given. These can be utilized to initiate any kind of radical chain reactionb yt ransforming substrates into the desired radical intermediates. Azo initiators,p eroxides, nitroxides, trialkylboranes, dialkyl zinc compounds, and type Ip hotoinitiators are discussed, as well as methods of redox-and sonochemical initiation. Methods of direct radical formation from the substrates, such as photoredoxc atalysis or high-energyi rradiation, are not included. The focus of this review lies on rather "low" temperatures in the range of 50 8Cd own to À78 8C, which can be useful to achievem ore selectiver eactions. Illustrative applications of such radical chain initiatorsi navariety of reactions are discussed, including stereoselective ones and polymerizations.Scheme1.Generalmechanism for radical chain reactions transforming substrates (S) into product (P) via intermediate radicals (iR), being initiatedw ith radicals generated from molecularinitiatorsX -Y.Scheme2.Classification of radicalgeneration from initiator molecules X-Y (D:thermal energy;h n:photochemically;)))): sonochemically).Scheme19. Applications of type-I photoinitiators in organics ynthesis.Scheme20. Initiation of athiol-enereaction with N-phenyltriazolinedione 40.Scheme21. Sonochemical initiation of radical reactions.
“…Subsequently, the trapping of 5 with a phosphorus nucleophile provides the desired product 3 b .The formation of C −P bonds by using derivatives other than those of tetrahydroisoquinoline were also investigated. In 2011, Renaud reported an efficient procedure that involved a thiophosphite‐mediated radical addition‐translocation‐cyclization (RATC) process to prepare functionalized five‐membered rings (Scheme ). This process is the first use of dicumyl peroxide (DCP) under photochemical conditions for small molecule synthesis.…”
Section: Photocatalytic Synthesis Of Phosphorus‐containing Compoundsmentioning
The vernal blooming of green chemistry has contributed to the development of visible light catalysis. Active radical species are generatedf rom catalytic amounts of photosensitizers,such as transition-metal complexes and organic dyes, upon visible light irradiation. Stoichiometrica mounts of oxidants, reductants, and radical initiators are avoidedi n most cases. Thus, reactions proceed under milder conditions with ab roader functional group tolerance than found by other methods. Photoredoxc atalysis has been used to form CÀCa nd CÀX( X= O, N, and S) bonds but is comparably underdeveloped in organophosphorus chemistry.H erein, we summarize advances in photoredox catalysis that involve organophosphorus chemistry.T he synthesis of organophosphorusc ompounds by photoredox catalysis, transition-metal complex/photoredoxd ual catalytic systems, andp hotoredox catalysis with phosphorus organocatalysts are discussed. The shortcomings and possible future trendso ft his chemistry are also presented.Scheme1.Various photocatalysts for the cross-couplingr eactionso ftetrahydroisoquinoline with dialkylphophonates and diaryl phosphine oxides[ ppy = 2phenylpyridine, bpy = 2,2'-bipyridine, DMF = N,N-dimethylformamide, AIBN = azobis(isobutyronitrile), PVA = poly(vinyl alcohol), BTF = benzotrifluoride].Scheme3.Thiophosphite-mediated RATC process to form five-membered ring and C sp 3 ÀPb ond.Scheme2.The mechanism for the photocatalyzed cross-coupling reaction [PC = Ir complex, Au complex, eosin Y, or rose bengal)].Scheme9.Direct CÀHp hosphorylationoft hiazoles in cross-coupling hydrogen evolution reaction and the proposed mechanism.Scheme11. Hetero-cross-dehydrogenative-coupling reaction of benzothiazoles and H-phosphonates.Scheme10. Hetero-cross-dehydrogenative-coupling reaction of dialkylphosphiteswith N-protected indole and the tentative reaction mechanism.
“…The preparation of five-membered ring via radical translocationcyclization (RTC) processes involving transient alkenyl radicals proved to be a particularly efficient process [8]. Alkenyl radicals can be generated directly from alkenyl halides [9,10] or by radical addition to a terminal alkyne [11][12][13][14][15][16][17][18][19]. The thiophenol-mediated radical addition-translocation-cyclization (RATC) process [20][21][22][23] is preparatively very useful since terminal alkynes are easily accessible [24].…”
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