61937-45-9Relevant academic research and scientific papers
Stereoselective synthesis of enamides by a Peterson reaction manifold
Fuerstner, Alois,Brehm, Christof,Cancho-Grande, Yolanda
, p. 3955 - 3957 (2007/10/03)
equation presented Vinylsilanes are converted into enamides by a sequence comprising epoxidation, nucleophilic ring opening of the resulting epoxysilanes with NaN3, and reduction of the azide, followed by a "one-pot" N-acylation/Peterson elimin
THE STEREOSELECTIVE CONVERSION OF VINYLSILANES TO γ-SUBSTITUTED ALLYLSILANES VIA HIGHER ORDER CUPRATES
Soderquist, John A.,Santiago, Braulio
, p. 5693 - 5696 (2007/10/02)
Pure cis-vinylsilanes are efficiently converted to cis-epoxysilanes which react smoothly with Li2Cu(CN)(CH2TMS)2 to provide the corresponding eryhro disilylated alcohol, in excellent yield and isomeric purity.Elimination of the elements of TMSOH affords e
Organosilicon compounds with functional groups proximate to silicon. XVII. Synthetic and mechanistic aspects of the lithiation of α,β-epoxyalkylsilanes and related α-heterosubstituted epoxides
Eisch, John J.,Galle, James E.
, p. 293 - 314 (2007/10/02)
A series of α-heterosubstituted epoxides, , has been found to undergo lithiation in the temperature range of -75 to -115 deg C at the C-H bond of the epoxide.The substituent Z could be Me3Si, Ph3Si, n-Bu3Sn, Ph3Sn, PhSO2, (OEt)2PO and Ph; the groups R and R' were H, Ph and n-C6H13; and the lithiating reagents were n-butyllithium, t-butyllithium and lithium diisopropylamide in donor media of THF or TMEDA.The lithiation occurs with retention of configuration and the resulting lithio-epoxide is unstable above 0 deg C, decomposing in a carbenoid manner.The lithiation is facile except for compounds where Z and R (an alkyl or aryl) are cis-oriented; where Z = R3Sn, lithiation occurs by tin-lithium, rather than hydrogen-lithium, exchange.The lithio-epoxides thereby generated can be quenched with various reagents to yield epoxides where the epoxide H has been replaced by D, Me3Sn, R, RCO and COOH.The utility of this procedure in organic synthesis is emphasized.Finally, the possible explanations for the acidity of such α-heterosubstituted epoxides and for the relative stability of the derived lithio-epoxides are considered and assessed.
Proprietes nucleophiles des carbenoides monohalogenes non fonctionnels
Villieras, J.,Kirschleger, B.,Tarhouni, R.,Rambaud, M.
, p. 470 - 478 (2007/10/02)
The coupling of non functionalised monohalocarbenoids R1-CXLi-R2 1 (R1 = alkyl, H ; R2 = H, CH3) with carbonyl compounds at -115 degree leads to the formation of lithium salts of halohydrins which readily give epoxides (via lithium halide elimination) at -95 degree in the presence of lithium bromide.The regiospecific synthesis of α-haloketones and α-haloaldehydes can be achieved by acylation of 1 with esters.A total lack of reactivity of 1 towards powerful alkylating electrophiles has been observed showing that they are not nucleophilic organometallics.The reactivity with carbonyl compounds seems to be promoted by the carbonyl-lithium (from the carbenoid) complexation.A correlation between nucleophilic/electrophilic properties of carbenoids (mono-, di- and trihalo-) and their assigned structure (metallocarbenium halides) is discussed.
Preparation des α-monohalogenoalkyllithiums non fonctionnels
Villieras, Jean,Tarhouni, Radhouane,Kirschleger, Bernard,Rambaud, Monique
, p. 825 - 830 (2007/10/02)
The preparation of very unstable α-monohaloalkyllithiums (carbenoids), potential electro- and nucleophiles, from easily accessible gem-halogenated alkanes, by halogen-lithium exchange at low temperatures is described.R-CHXLi type carbenoids (R aryl, H or CH3 ; X = Cl, Br) are obtained by bromine-lithium exchange in a THF-ether-pentane mixture at temperatures below -115 deg C.The α-silylated organolithiums Me3SiCXLiR (R = H, alkyl; X = Cl, Br) despite their greater stability, must be prepared at the same temperature; secondary reactions are limited by the use of an inverse addition of secondary butyllithium.CH2XLi an RCXLiMe carbenoids (R = H, CH3 ; X = Cl, Br) have to be prepared in the presence of one equivalent of lithium bromide in order to reduce the halogen-lithium carbenoid interaction which is responsible for their instability.
SILICON IN SYTHESIS-17 CHLROMETHYL(TRIMETHYLSILYL)LITHIUM-A NEW REAGENT FOR THE DIRECT CONVERSION OF ALDEHYDES AND KETONES INTO α,β-EPOXYTRIMETHYLSILANES
Burford, Clifford,Cooke, Frank,Roy, Glenn,Magnus, Philip
, p. 867 - 876 (2007/10/02)
Treatment of chloromethyltrimethylsilane 1 with sec-BuLi at -78 deg produces chloromethyl(trimethylsilyl)lithium 4.Treatment of 4 with a wide range of aldehydes and ketones gives α,β-epoxytrimethylsilanes 5-28, which on acidic hydrolysis give homologated aldehydes.
