Propenes trimethylsilyl

Trienes possessing /V-acyl-l-aza-1,3-butadiene units have been prepared by the reaction of ( )-3-phenyl-2-propenal(trimethylsilyl)oxime67 and ( )-3-phenyl-2-propenal(7er/-butyldiniethylsilyl) oxime68 with acylating agents. The product trienes underwent stereocontrolled hetero-IMDA reaction. 

A variable pressure oil pump was used in this distillation. Approximately 10 g of a volatile component, consisting mostly of hexamethyl-disiloxane, was obtained at room temperature (15 (in) before the forerun. The forerun contained the desired product and mineral oil from the n-butyllithium solution. The pot residue was about 5 g. The submitters find the disilyl compound thus obtained is contaminated with a trace amount of mineral oil and 4-6% of a vinylsilane, probably 2-methyl-l-trimethylsiloxy-3-trimethylsilyl-2-propene. This impurity becomes quite significant if the reaction medium is less polar than the one described (e.g., too much hexane from n-butyllithium is allowed to remain behind). The spectral properties of the desired product... 

The discovery of palladium trimethylenemethane (TMM) cycloadditions by Trost and Chan over two decades ago constitutes one of the significant advancements in ring-construction methodology [1]. In their seminal work it was shown that in the presence of a palladium(O) catalyst, 2-[(trimethylsilyl)methyl]-2-propen-l-yl acetate (1) generates a TMM-Pd intermediate (2) that serves as the all-carbon 1,3-di-pole. It was further demonstrated that (2) could be efficiently trapped by an electron-deficient olefin to give a methylenecyclopentane via a [3-1-2] cycloaddition (Eq. 1). 

Intramolecular [3-1-2] cycloadditions, i.e., having the TMM moiety and the acceptor linked by a tether, have great synthetic utility in polycarbocycle construction. The construction of 5.5, 6.5, and 7.5 ring systems has been demonstrated with this methodology [21-25]. A number of efficient routes to acyclic precursors were developed (Scheme 2.11). The organometallic reagent (31), generated from 2-bro-mo-3-(trimethylsilyl)propene (32) [26], is a key component in the construction of... 

Chelation control, as indicated in 5, is also a suitable model for rationalizing the stereochemical outcome of titanium tetrachloride mediated additions of 3,3-dimelhyl-2-trimethylsilyl-oxy-l-butenc (6) or l-methoxy-2-methyl-l-trimethylsilyloxy-l-propene (7) to 3-benzyloxy-2-methylpropanal (4). In both cases, there is almost exclusive formation of the chelate-controlled product (95 5 and >97 3, respectively)13. 

A synthetically useful example uses 2-[(trimethylsilyl)methyl]-2-propen-1-yl acetate (95), which is commercially available, and a palladium or other transition metal catalyst to generate 96 or 97, which adds to double bonds, to give, in... 

In the presence of copper and palladium catalysts, terminal alkynes 1222 react with trimethylsilyl azide and allyl methyl carbonate to provide 2,4-disubstituted 1,2,3-triazoles 1223 in moderate to good yield. Isomerization of the allyl substituent in the presence of a ruthenium catalyst gives 4-substituted 2-(l-propen-l-yl)-2//-l,2,3-triazoles 1224. 

Protonation of tetrakis(trimethylsilyl)allene 33 with HSO3F/ SbF5 (1 1) gives the 1,1,3,3-tetrakis(trimethylsilyl)-l-propen-2-yl cation 34. The isomeric allyl cation 35 is not formed (12, 44). 

The efficiency of the [2 + 2]-cycloadditions of 417 was utilized in a strategy for the synthesis of cephalosporin derivatives that carry an acetone or acetic acid ester group in the 3-position (Scheme 6.88) [175]. Liberated in the presence of 2-(trimethylsilyl-oxy)propene, 417 underwent cycloaddition leading to 435, treatment of which with tetrabutylammonium or hydrogen fluoride furnished the A3-cephalosporin 436 admixed with the A2-isomer. This mixture was converted to pure 436 by an oxidation-reduction sequence. In addition to the trimethylsilylenol ether of acetone, the... 

The unusual amino acid (S)-2-amino-(Z)-3,5-hexadienoic acid (269), which is a component of the toxic y-glutamyl dipeptide isolated from the defensive glands of the Colorado beetle [209], has been synthesized along Scheme 17, after two initial attempts had proved unsuccessful due to the instability of 269 towards various oxidation conditions [210]. Scheme 17 relies on the hydrolysis of an ortho ester to generate the required carboxylic acid. Thus, the L-serine aldehyde equivalent 270 was treated with ( )-l-trimethylsilyl-l-propene-3-boronate to give the addition product 271. Reaction of 271 with KH gave the stereochemically pure (Z)-diene 272. Mild acid treatment of 272 followed by... 

They transformed L-serine in seven steps to the iV-2-(trimethylsilyl)ethyl-sulfonyl(SES)-protected aziridine 104. The latter reacted with the lithio-an-ion of ( )-3-phenyl-l-(phenylsulfonyl)-2-propene (105) to a diastereomeric mixture of the sulfones 106 (Scheme 27). This mixture was treated with TBAF, yielding the pyrrolidine 107 as a single diastereoisomer with 2,3-frans-2,5-czs-configuration previously observed for 5-endo-trig cyclizations of this type. In three additional steps the pyrrolidine 107 was transformed to (+)-preussin (2), with 5% yield overall and in twelve steps altogether. 

Fluorotris(trimethylsilyl)methane reacted with 2 M equiv. of an aromatic aldehyde in the presence of potassium fluoride/18-crown-6 to give 1,3-disubstituted 2-fluoro-2-propen-1-ols (27) in 65-78% yields [51] (Scheme 7). 

STEREOSPECIFIC REDUCTION OF PROPARGYL ALCOHOLS (E)-3-TRIMETHYLSILYL-2-PR0PEN-l-0L (2-Propen-l-ol, 3-(tr1i ethy1s11yl)-, (E)-)... 

STEREOSPECIFIC REDUCTION OF PROPARGYL ALCOHOLS (E)-3-TRIMETHYLSILYL-2-PROPEN-1-0L... 

Several methods have been reported for the formation of cyclopentanes by 2 + 3 cycloadditions.908 One type involves reagents that produce intermediates 90 or 91.9"9 A synthetically useful example910 uses 2-[(trimethylsilyl)methyl]-2-propen-l-yl acetate (89) (which is com-... 

Trimethylsilyl ethers and esters.i The reaction of alcohols and allyltrimethyl-silane in acetonitrile with TsOH as catalyst (70 80°, 1 3 hours) results in trimethyl-silyl ethers in 85-95% yield with elimination of propene. The same reaction with carboxylic acids results in trimclhylsilyl esters. Phenols do not undergo this reaction. 

Pentene 4.5-Difluoro-2-mcthyl-5-trimethylsilyl- ElOb,. 421 (R3Si-CF=CF2 + En- Li) Propene 1.2-Difluoro-l-triethylsilyl-121 Ob,. 421(Educt)... 

Trimethylsilyl-oL,fi-enones or enals.2 These compounds can be obtained by the same sequence from l-methoxy-3-phenylthio-3-trimethylsilyl-l-propene, 2. 

Methoxy(phenylthio)trimethylsilyl-methyllithium, 182 l-Methoxy-3-phenylthio-3-trimethyl-silyl-l-propene, 182 l-Methoxy-3-phenylthio-3-trimethyl-silyl-l-propenyl-3-lithium, 182 (Z) -1 -Methoxy-4-(trimethylsilyl)-1 -butene-3-yne, 179... 

Silyl-l,3-dienes undergo anodic methoxylation in methanol to give 1,4-addition products with an allylsilane structure as intermediates. Therefore, they are further oxidized to give l,l,4-trimethoxy-2-butene derivatives as the final products. The products are easily hydrolyzed to provide the corresponding y-methoxy-a, /t-unsaUirated aldehydes. Since 1-trimethylsilyl-l,3-dienes are readily prepared by the reaction of the anion of l,3-bis(trimethylsilyl)propene with aldehydes or ketones, l,3-bis(trhnethylsilyl)propene offers a, /i-formylvinyl anion equivalent for the reaction with carbonyl compounds (equation 15)16. 

Whereas an allylsilane can serve as an allyl anion synthon, the reaction of 1,3-bis(silyl)propene with electrophiles can afford the 1,3-disubstituted propene. Thus, treatment of a mixture of (If)- and (Z)-2-aryl-l,3-bis(trimethylsilyl)propenes 5 with 2 equivalents of NBS at —78 °C stereoselectively yields the corresponding (Z)-2-aryl-l,3-dibromopropene 6. When 1 equivalent of NBS is employed, the monobromo product 7 is obtained (equation 5). The reactions apparently proceed via the pattern of sequential displacement of allylsilane moieties40,41. 

The reagent can also be converted into 3-trimethylsilyl-1,3-bis-(ptaenyl-seleno)propene (2), a useful reagent for preparation of silyl enones. 

Hydroxymethyl-3-allyltrimethylsilane. 2-(Trimethylsilylmethyl)-3 acetoxy-1 -propene. 2-(Trimethylsilyl)n]ethylallyl iodide. 

Trimethylsilyl-1,3-bis-(phenylseleno)propene, 60 Trimethylsilyl-5-chloro-l, 4-dienes, 49 Trimethylsilyldiazomethane, 573-574 2-Tnmethylsilylethanol, 4, 574 P (Trimethylsilyl)ethyllithium, 574-575 2-Trimethylsilylfuranes, 577 3 -Tnmethylsiiyl-4-hydroxy-1 -alkenes, 175 N-(TrimethyIsilyl)imidazole, 575 Trimethylsilyllithinm, 575 Trimethylsilylmethanethiol, 576 1 -Trimethylsilyl-1 -methoxyallene, 577 2-(Trimethylsilylmethyl)-3-acetoxy-1 -propene, 578-579... 

Bicyciic methy/enecyclopentanes. Trostand Chan2 have extended their synthesis of mcthylenecyclopentanes by cycloaddition of trimethylenemethanepalladium complexes to alkenes (9,454-455J3 to an intramolecular [3 + 2] cycloaddition to give bicyciic mcthylenecyclopentanes. The substrates (2) can be prepared by reaction of Ihc Grignard reagent prepared from 2-bromo-3-(trimethylsilyl)propene (1) with a suitable bifunctional aldehyde (equation I). 

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