Hydrosilylation of enones: platinum divinyltetramethyldisiloxane complex in the preparation of triisopropylsilyl and triphenylsilyl enol ethers

Johnson, Carl R.; Raheja, Raj K.

doi:10.1021/jo00088a006

Cited by 53 publications

(28 citation statements)

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“…High selectivity for the β-(E)-vinylsilane can be achieved through the use of Pt(DVDS)/P(i-BuNCH 2 CH 2 ) 3 N (DVDS = [(H 2 C=CH) Me 2 Si] 2 O) and exhibits high functional group tolerance including ethers, halides, cyano groups, esters, and alcohols (eq 13). 37 It should be noted that triethylsilane has been more widely studied for the hydrosilylation of carbonyls, and it would appear that some, but certainly not all, of the methods used for that reagent can be successfully applied to Ph 3 SiH. 22 31 Hydrosilylation of carbonyls with Ph 3 SiH can provide direct access to the corresponding triphenylsilyl ethers via a Rh 29,32 complex.…”

Section: Alkynesmentioning

confidence: 99%

Triphenylsilane

Sano

Torres

Maleczka

2007

Encyclopedia of Reagents for Organic Synthesis

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Section: Alkynesmentioning

confidence: 99%

Triphenylsilane

Sano

Torres

Maleczka

2007

Encyclopedia of Reagents for Organic Synthesis

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“…Triisopropylsilyl and triphenylsilyl enol ethers have been prepared from cyclic enones using Karstedt's catalyst. 36 The reaction typically proceeded within 15 min at 100 • C and few hours at rt with cyclopentenones, cyclohexones, and cycloheptenones (eq 15). (15) Not only can hindered silyl enol ethers be prepared, but the method is also compatible with a broad range of silanes (TES, TBS, DMPS, Si(OEt) 3 , TIPS, TPhS).…”

mentioning

confidence: 99%

Tris(1,1,3,3-tetramethyl-1,3-divinyldisiloxane)diplatinum

Lebel

2011

Encyclopedia of Reagents for Organic Synthesis

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“…Eventually we discovered that reduction of the enone using catalytic platinum divinyltetramethyl disiloxane complex (Karstedt's catalyst) in the presence triisopropylsilane gave the TIPS-silyl enol ether 10 in excellent yield. 18 Less bulky silanes such as TES-H and TBS-H provided a significant amount of the saturated ketone 11 (~20-30%), presumably via silane dimerization that formed molecular hydrogen that simply reduced the alkene in the presence of the platinum catalyst. 19…”

mentioning

confidence: 99%

Concise, Enantioselective Total Synthesis of (−)-Alstonerine

Miller

Martin

2007

Org. Lett.

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A novel enantioselective total synthesis of (-)-alstonerine has been completed that requires only 1 5 steps from L-tryptophan. The synthesis features the first application of a Pauson-Khand reaction t o synthesize an azabridged bicyclic skeleton.The macroline/sarpagine class of indole alkaloids is a rich source of biologically active natural products, some of which exhibit hypotensive, antiamoebic, and antimalarial activities. 1 For example, alstonerine (1) has recently been reported to exhibit cytotoxic activity against two human lung cancer cell lines. 2 The alkaloids of this family contain an azabicyclo[3.3.1] substructure that is annelated to an indole ring. It is thus fitting that a number of strategies have been devised to access this structural motif including sequential Pictet-Spengler and Dieckmann condensations, 3 ring-closing metathesis, 4 phosphine-catalyzed [4+2] annulation/ Friedel-Crafts cyclization, 5 or aza-Diels-Alder/intramolecular Heck reaction. 6 As a representative member of the macroline/sarpagine family, two total syntheses and one formal synthesis of 1 have been reported. 5, 7In the context of a longstanding interest in alkaloid synthesis, we have been intrigued by designing and developing novel and general strategies for the facile preparation of representative members of different alkaloid families. 8 We have recently explored a number of transition metal catalyzed reactions for the construction of ring systems common to a number of alkaloids. In the context of some investigations toward developing some new cascade reactions, 9 we became interested in examining the potential of the Pauson-Khand reaction (PKR) for alkaloid synthesis. The intramolecular version of the PKR has been applied to the syntheses of a few natural products, 10 but its use has overwhelmingly been limited to forming fused bicyclo-[3.3.0]octenones and bicyclo[4.3.0]nonenones. 11, 12Our ongoing efforts to develop concise routes for the elaboration of azabridged bicyclic structures led us to query whether the scope of the PKR might be extended to include cyclizations of cis-2,6-disubstituted piperidine enynes. Considering the absolute lack of precedent for such a PKR, the simple model substrate 4 was first prepared to explore the feasibility of such a construction (Scheme 1). Thus, by analogy with previous work in our laboratories, 4, 13 reaction of 4-methoxypyridine (2) with the anion derived from trimethylsilylacetylene in the presence of Cbz-Cl gave the unsaturated piperidinone 3. Lewis acid mediated conjugate addition of allyltribuyltin followed by treatment of the intermediate silyl acetylene with TBAF provided the enyne substrate 4 in >19:1 diastereoselectivity. To our delight, the ensuing PKR proceeded cleanly to give 5 as a single diastereomer. To our knowledge, this represents the first example of a PKR to provide an azabridged bicyclic product.Correspondence to: Stephen F. Martin. Having thus established the underlying viability of using PKRs to form azabicyclo[3.3.1] bicyclononanes fused with cyclop...

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Hydrosilylation of enones: platinum divinyltetramethyldisiloxane complex in the preparation of triisopropylsilyl and triphenylsilyl enol ethers

Cited by 53 publications

References 0 publications

Triphenylsilane

Triphenylsilane

Tris(1,1,3,3-tetramethyl-1,3-divinyldisiloxane)diplatinum

Concise, Enantioselective Total Synthesis of (−)-Alstonerine

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