146566-29-2Relevant academic research and scientific papers
Regioselective Silylations of Propargyl and Allyl Pivalates through Ca-Promoted Reductive C(sp3)-O Bond Cleavage
Zhang, Tianyuan,Zheng, Suhua,Kobayashi, Taro,Maekawa, Hirofumi
supporting information, p. 7129 - 7133 (2021/09/18)
A practical protocol for the regioselective preparation of 3-phenylpropargylsilanes and 3-phenylallylsilanes in yields of 36-77 and 48-86%, respectively, from readily accessible 3-phenylpropargyl and 1-phenylallyl pivalates was developed through reductive C(sp3)-O bond cleavage. This method represents the first example of the direct application of vastly abundant calcium granules to a reductive coupling reaction. A broad range of propargylsilanes and allylsilanes are simply prepared using easy-to-handle pivalates and chlorotrimethylsilane under mild catalyst-free and additive-free conditions.
Synthesis of Enantioenriched Allylic Silanes via Nickel-Catalyzed Reductive Cross-Coupling
Hofstra, Julie L.,Cherney, Alan H.,Ordner, Ciara M.,Reisman, Sarah E.
supporting information, p. 139 - 142 (2018/01/17)
An asymmetric Ni-catalyzed reductive cross-coupling has been developed to prepare enantioenriched allylic silanes. This enantioselective reductive alkenylation proceeds under mild conditions and exhibits good functional group tolerance. The chiral allylic silanes prepared here undergo a variety of stereospecific transformations, including intramolecular Hosomi-Sakurai reactions, to set vicinal stereogenic centers with excellent transfer of chirality.
Synthesis of allylsilanes by reductive lithiation of thioethers
Streiff, Stephane,Ribeiro, Nigel,Desaubry, Laurent
, p. 7592 - 7598 (2007/10/03)
Although much work in reductive lithiation has been done, the utilization of allylthioethers bearing various substituents to prepare allylsilanes has not been explored. The main reason clearly stems from the anticipated lack of regioselectivity. We describe herein the first study on the regioselectivity of the reductive silylation involving dissymmetric allylthioethers. We surveyed a broad spectrum of parameters and showed that this process displays a great dependence of the reaction conditions. We also discovered that an electron transporter, DBB or naphthalene, can cleave THF at room temperature by sonication, to generate a strong base, 4-lithiobutoxide. This feature was successfully exploited to the straightforward synthesis of bis-silanes in one pot. Examples are provided for maximizing both the chemical yield and the regioselectivity of the reductive silylation through the tuning of the reaction conditions. By changing these conditions, several allylsilanes can be selectively synthesized from one thioether.
Silylation of Allylic Trifluoroacetates and Acetates Using Organodisilanes Catalyzed by Palladium Complex
Tsuji, Yasushi,Funato, Masahiro,Ozawa, Masakatsu,Ogiyama, Hiroaki,Kajita, Satoshi,Kawamura, Takashi
, p. 5779 - 5787 (2007/10/03)
Silylation of allylic acetates (1) using organodisilanes (2) was carried out in the presence of a catalytic amount of Pd(DBA)2-LiCl at 100 deg C. The silylation proceeded smoothly without β-hydrogen elimination of a resulting (?-allyl)palladium intermediate. The added chloride salt such as LiCl or NaCl was indispensable for the catalytic activity. On the other hand, remarkable improvement of the silylation was realized by employing allylic trifluoroacetates (4) in place of the acetates (1) as the substrates. The silylation proceeded even at room temperature, and the added chloride salts was not necessary as the catalyst component. In the silylation, transmetalation of the disilanes (2) with (η3-allyl)palladium intermediate (7) might be a critical step in the catalytic cycle. Model reactions for the transmetalation were carried out.
A Regioselective and Stereospecific Synthesis of Allylsilanes from Secondary Allylic Alcohol Derivatives
Fleming, Ian,Higgins, Dick,Lawrence, Nicholas J.,Thomas, Andrew P.
, p. 3331 - 3350 (2007/10/02)
Primary and secondary allylic acetates and benzoates react with the dimethyl(phenyl)silyl-cuprate reagent to give allylsilanes, provided that the THF in which the cuprate is prepared is diluted with ether before addition of the allylic ester.The reaction is reasonably regioselective in some cases: (i) when the allylic system is more-substituted at one end than the other, as in the reactions 4->5 and 9->10; (ii) when the steric hindrance at one end is neopentyl-like, as in the reactions 15->16; and (iii) when the disubstituted double bond has the Z configuration, as in th e reactions Z-19->E-21 or, better, because the silyl group is becoming attached to the less-sterically hindered end of the allylic system, Z-20->E-22.The regioselectivity is better if a phenyl carbamate is used in place of the ester, and a three-step protocol assembling the mixed cuprate on the leaving group is used, as in the reactions 23->24 and E- or Z-29->E-21, or, best of all, because the silyl group is again becoming attached to the less-sterically hindered end of the allylic system, E- or Z-30->E-22.This sequence works well to move the silyl group onto the more substituted end of an allyl system, but only when the move is from a secondary allylic carbamate to a tertiary allylsilane, as in the reaction 38->39.Allyl(trimethyl)silanes can be made using alkyl- or aryl-cuprates on trimethylsilyl-containing allylic esters and carbamates, as in the reactions 40->41, and 43->44.The reaction of the silyl-cuprate with allylic esters and the three-step sequence with the allylic carbamates are stereochemically complementary, the former being stereospecifically anti and the latter stereospecifically syn.Homochiral allylsilanes can be ma de by these methods with high levels of stereospecificity, as shown by the synthesis of the allylsilanes 54, 58 and 59.
A Regiocontrolled and Stereocontrolled Synthesis of Allylsilanes from β-Silyl Enolates
Fleming, Ian,Gil, Salvador,Sarkar, Achintya K.,Schmidlin, Tibur
, p. 3351 - 3362 (2007/10/02)
The α-lithiated diphenylphosphine oxides 3 react with methyl iodide to give the phosphine oxides 4 and 5 in a ratio 3-4:1.The corresponding reaction with aldehydes gives all four diastereomeric alcohols 7-10, which are not suitable for the synthesis of allylsilanes by a Wittig-Horner reaction.The β-dimethyl(phenyl)silyl enolates 13-15 and 25-28 react with aldehydes to give aldol products with high diastereoselectivity.The benzyl and allyl ester groups can be cleaved from these aldols to give the acids 16-18 and 29-32.The acids, in turn, can be induced to undergo dec arboxylative elimination stereospecifically either in a syn or an anti sense to give the allylsilanes 19, 20, 23, 24, 33, 34 and 39-41.A similar series of reactions can be carried out with the β-trimethylsilyl enolates 45 and 46 giving the allylsilanes 49, 50, 53 and 54.
Asymmetric Synthesis Catalyzed by Chiral Ferrocenylphosphine-Transition-Metal Complexes. 3. Preparation of Optically Active Allylsilanes by Palladium-Catalyzed Asymmetric Grignard Cross-Coupling
Hayashi, Tamio,Konishi, Mitsuo,Okamoto, Yasuo,Kabeta, Keiji,Kumada, Makoto
, p. 3772 - 3781 (2007/10/02)
Asymmetric cross-coupling of the - or -Grignard reagent with alkenyl bromides in the presence of a chiral ferrocenylphosphine-palladium complex, dichloroethylamine>palladium(II) (PdCl2), as a catalyst, gave optically active allylsilanes which contain an asymmetric carbon atom directly bonded to the silicon atom, e.g., (R)-3-phenyl-3-(trimethylsilyl)propene (3a) (95percent ee), (R,E)-1-phenyl-1-(trimethylsilyl)-2-butene (3b) (85percent ee), (R,Z)-3b (24percent ee), (R,E)-1,3-diphenyl-3- (trimethylsilyl)propene (3c) (95percent ee), (S,E)-1-phenyl-3-(trimethylsilyl)-1-butene (14c) (71percent ee), (S,Z)-14c (59percent ee), (S,E)-1-phenyl-3-(triethylsilyl)-1-butene (16c) (93percent ee), (S,E)-3-(triethylsilyl)-2-pentene (16b) (85percent ee), (S,E,E)-2-(dimethylphenylsilyl)-3,5-heptadiene (15d) (45percent ee), and 1-cyclopentene (21) (37percent ee).The configuration and enantiomeric purity of the allylsilanes were determined with the aid of stereoselective oxidative cleavage of the carbon-silicon bond in optically active alkylsilanes.
Diastereoselective Aldol Reactions of β-Silylenolates: A New Regiocontrolled Synthesis of Allylsilanes
Fleming, Ian,Sarkar, Achintya K.
, p. 1199 - 1201 (2007/10/02)
Allylsilanes are prepared stereospecifically trans (10) or cis (12) and with complete regiocontrol by decarboxylative elimination of the β-hydroxy acids (9).
