Silylative Carbocyclization of Allenyl-carbonyl Units with Et<sub>3</sub>SiH Catalyzed by Rhodium:  Cis-Stereoselective Synthesis of Homoallylic Cycloalkanols

Kang, Suk‐Ku; Hong, Young‐Taek; Lee, Joon‐Hwan; Kim, Won-Yeol; Lee, Inhee; Yu, Chan‐Mo

doi:10.1021/ol034787k

Cited by 53 publications

(8 citation statements)

References 26 publications

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“…The cis (δ 5.28-5.37) and trans (δ 5.65-5.75) protons relative to silicon of α-triethylsilyl vinylsilanes are quite distinct, both for other substrates in this study, and in closely related 1-cyclohexenyl-triethylvinylsilane reported elsewhere. 28 This result indicates that the trans addition phenomenon is general-that it applies to terminal alkynes in addition to internal alkynes. The importance of the result with the sterically demanding terminal alkynes is mechanistically significant.…”

Section: (1)mentioning

confidence: 92%

Alkyne Hydrosilylation Catalyzed by a Cationic Ruthenium Complex: Efficient and General Trans Addition

2005

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The complex [Cp*Ru(MeCN) 3 ]PF 6 is shown to catalyze the hydrosilylation of a wide range of alkynes. Terminal alkynes afford access to α-vinylsilane products with good regioselectivity. Deuterium labeling studies indicate a clean trans addition process is at work. The same complex is active in internal alkyne hydrosilylation, where absolute selectivity for the trans addition process is maintained. Several internal alkyne substrate classes, including propargylic alcohols and α,β-alkynyl carbonyl compounds, allow regioselective vinylsilane formation. The tolerance of a wide range of silanes is noteworthy, including alkyl-, aryl-, alkoxy-, and halosilanes. This advantage is demonstrated in the direct synthesis of triene substrates for silicon-tethered intramolecular DielsAlder cycloadditions.Metal-catalyzed simple addition reactions of alkynes are important synthetic processes and are desirable from the standpoint of synthetic efficiency and atom economy. Questions of regioand stereoselectivity become important considerations, and pathways affording syn addition are plentiful and well studied. Metal catalysis of trans addition processes-where new bonds must be formed on opposite sides of the alkyne-have only rarely been observed. Indeed, the possibility of creating direct trans addition processes which do not involve initial cis addition followed by E/Z isomerization is an exciting target. This paper describes our work studying trans addition processes in alkyne hydrosilylation with ruthenium catalysts to afford vinylsilane products.Vinyl-metal species are extremely important building blocks in organic synthesis. 1,2 Among these, vinylsilanes play a growing role due to their low cost, low toxicity, ease of handling, and simplicity of byproduct removal. Particularly significant is the potential of vinylsilanes as nucleophilic partners in palladium-catalyzed cross-coupling reactions. 3 Vinylsilanes are also useful as acceptors in conjugate addition reactions, as masked ketones through Tamao-Fleming oxidation, 4 and as terminators for cation cyclizations. 5 Unlike most other organometallic reagents-including in many cases organoboranes and organostannanes-vinylsilanes can be readily carried through many synthetic operations.However, the utility of vinylsilanes has been inhibited by the inconvenience of accessing stereo-and regio-defined vinylmetal compounds. Among the possible routes to these compounds, hydrosilylation of alkynes represents the most straightforward, atom-economical access. 6 Classical platinum catalysis 7 provides clean cis addition to (E)-vinylsilanes (2), and ligand tuning has made this a very regioselective process as well. 8 In addition, there has been significant progress using a variety of metal-catalyzed approaches to provide stereodefined, 1,2-substituted vinylsilanes of the form 1 or 2. There has been no reported general access to bmtrost@stanford.edu. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript 1,1-disubstituted vinylsilanes 9 (3) a...

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Section: (1)mentioning

confidence: 92%

Alkyne Hydrosilylation Catalyzed by a Cationic Ruthenium Complex: Efficient and General Trans Addition

2005

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“…Yu et al observed a Rh-catalyzed silylcarbocyclization of allenyl aldehydes and ketones 841 via the silylrhodation of the allene-1,2-addition to the CO bond-reductive elimination mechanism to afford 2-vinylic cyclic alcohols cis - 842 . Recently, Shibata et al.…”

Section: Miscellaneous Reactionsmentioning

confidence: 99%

Some Typical Advances in the Synthetic Applications of Allenes

2005

Chem. Rev.

1,348

256

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In 1989, Kakiuchi et al. reported that under irridation propadiene can undergo [2+2]-cycloaddition with R,β-unsaturated cyclohexenones to afford methylene-cyclobutane-containing bicyclic products 1 (Scheme 1). 6 Shi et al. reported that under the catalysis of DABCO, N-tosylated imines 2 can undergo [2+2]cycloaddition with 2,3-butadienoate or 3,4-pentadien-2-one to afford azetidine derivatives 3. 7 The reaction proceeded via the nucleophilic addition of DABCO to the electron-deficient allene forming 4-and 5-type intermediate, which may undergo 1,2-addition with the imines to afford 6. Intramolecular conjugate Scheme 1

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“…The transition metal‐catalyzed allylation of aldehydes and imines has attracted considerable attention due to the synthetic utility of corresponding homoallylic alcohol and amine products as well as the interesting reactivity of the allyl‐transition metal complex during the reaction 1,2,3,4. To accomplish such allylations using a catalytic amount of transition metal complexes and allylic acetates or allenes as starting materials, a range of protocols utilizing stoichiometric amounts of organometallic reagents (tin,2a,b,d,e,3c zinc,2c,h,i,j,m,p indium,2f,3a,b borane,2o,s,t,u and silane2k,q,r) which reverse the reactivity of the allyl‐metal complexes from electrophilic to nucleophilic have been investigated. Recently, the reactions of nucleophilic allyl‐iridium complexes were reported under transfer hydrogenation conditions where the use of metallic reductants were avoided 5…”

Section: Optimization Of the Reductive Cyclization Of Allene‐aldehydementioning

confidence: 99%

Platinum(II)‐Catalyzed Allylation of CO and CN Bonds under Hydrogenation Conditions

et al. 2010

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Abstract:The nucleophilic addition of allylplatinum to a range of electrophiles including carbonyls, oximes, and hydrazones was examined. Platinum(II) catalysts and allene substrates were subject to hydrogenation conditions to generate nucleophilic allylplatinum complexes without using a stoichiometric amount of toxic and sensitive organometallic reagents. The allylplatinum intermediates reacted with C=O and C=N bonds to produce the corresponding homoallylic alcohol and amine derivatives in good yield. The Pt-catalyzed allylation of C=N bonds is the first example performed under hydrogenation conditions. A reaction mechanism initiated with the hydrometalation of allenes by Pt À H species is proposed based on deuterium labeling studies.Keywords: allylation; cyclization; hydrazones; hydrogenation; platinumThe transition metal-catalyzed allylation of aldehydes and imines has attracted considerable attention due to the synthetic utility of corresponding homoallylic alcohol and amine products as well as the interesting reactivity of the allyl-transition metal complex during the reaction. [1,2,3,4] To accomplish such allylations using a catalytic amount of transition metal complexes and allylic acetates or allenes as starting materials, a range of protocols utilizing stoichiometric amounts of organometallic reagents (tin, [2a,b,d,e,3c] zinc, [2c,h,i,j,m,p] indium, [2f,3a,b] borane, [2o,s,t,u] and silane [2k,q,r] ) which reverse the reactivity of the allyl-metal complexes from electrophilic to nucleophilic have been investigated. Recently, the reactions of nucleophilic allyl-iridium complexes were reported under transfer hydrogenation conditions where the use of metallic reductants were avoided.[5]Our continuing effort to develop nucleophilic Pt complex-catalyzed reactions under environmentally benign conditions without the use of large amounts of organometallic reagents prompts us to examine the reaction conditions to form a nucleophilic allyl-platinum complex from allenes, Pt catalysts, and hydrogen. Similar to allyl-palladium complexes, allyl-platinum complexes have been applied to electrophilic catalytic reactions such as allylic alkylations but, to the best of our knowledge, there is no report of the reaction of nucleophilic allyl-platinum complexes.[6] Based on Ptcatalyzed hydrogenative coupling reactions using a range of p systems investigated by our group, [7] Pt À H species formed from the Pt complex and hydrogen react with the allene to form a nucleophilic allyl-platinum species. This paper reports the Pt-catalyzed hydrogen-mediated reductive cyclization of allene-carbonyls, allene-oximes and allene-hydrazones where nucleophilic allyl-platinum complexes were generated without large amounts of organometallic reagents. A remarkable aspect of this protocol is that Pt-catalyzed allylations of the ketone and carbon-nitrogen double bonds (e.g., allyl-oximes and allyl-hydrazones) were realized under hydrogenation conditions for the first time. [8,9] Table 1 summarizes the reaction optimization process. Compound...

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Silylative Carbocyclization of Allenyl-carbonyl Units with Et₃SiH Catalyzed by Rhodium: Cis-Stereoselective Synthesis of Homoallylic Cycloalkanols

Cited by 53 publications

References 26 publications

Alkyne Hydrosilylation Catalyzed by a Cationic Ruthenium Complex: Efficient and General Trans Addition

Alkyne Hydrosilylation Catalyzed by a Cationic Ruthenium Complex: Efficient and General Trans Addition

Some Typical Advances in the Synthetic Applications of Allenes

Platinum(II)‐Catalyzed Allylation of CO and CN Bonds under Hydrogenation Conditions

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Silylative Carbocyclization of Allenyl-carbonyl Units with Et3SiH Catalyzed by Rhodium: Cis-Stereoselective Synthesis of Homoallylic Cycloalkanols

Cited by 53 publications

References 26 publications

Alkyne Hydrosilylation Catalyzed by a Cationic Ruthenium Complex: Efficient and General Trans Addition

Alkyne Hydrosilylation Catalyzed by a Cationic Ruthenium Complex: Efficient and General Trans Addition

Some Typical Advances in the Synthetic Applications of Allenes

Platinum(II)‐Catalyzed Allylation of CO and CN Bonds under Hydrogenation Conditions

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Silylative Carbocyclization of Allenyl-carbonyl Units with Et₃SiH Catalyzed by Rhodium: Cis-Stereoselective Synthesis of Homoallylic Cycloalkanols