- Continuous-flow Si-H functionalizations of hydrosilanesviasequential organolithium reactions catalyzed by potassiumtert-butoxide
-
We herein report an atom-economic flow approach to the selective and sequential mono-, di-, and tri-functionalizations of unactivated hydrosilanesviaserial organolithium reactions catalyzed by earth-abundant metal compounds. Based on the screening of various additives, we found that catalytic potassiumtert-butoxide (t-BuOK) facilitates the rapid reaction of organolithiums with hydrosilanes. Using a flow microreactor system, various organolithiums bearing functional groups were efficiently generatedin situunder mild conditions and consecutively reacted with hydrosilanes in the presence oft-BuOK within 1 min. We also successfully conducted the di-funtionalizations of dihydrosilane by sequential organolithium reactions, extending to a gram-scale-synthesis. Finally, the combinatorial functionalizations of trihydrosilane were achieved to give every conceivable combination of tetrasubstituted organosilane libraries based on a precise reaction control using an integrated one-flow system.
- Lee, Hyune-Jea,Kwak, Changmo,Kim, Dong-Pyo,Kim, Heejin
-
supporting information
p. 1193 - 1199
(2021/02/26)
-
- Catalytic protodeboronation of pinacol boronic esters: Formal anti-Markovnikov hydromethylation of alkenes
-
Pinacol boronic esters are highly valuable building blocks in organic synthesis. In contrast to the many protocols available on the functionalizing deboronation of alkyl boronic esters, protodeboronation is not well developed. Herein we report catalytic protodeboronation of 1°, 2° and 3° alkyl boronic esters utilizing a radical approach. Paired with a Matteson-CH2-homologation, our protocol allows for formal anti-Markovnikov alkene hydromethylation, a valuable but unknown transformation. The hydromethylation sequence was applied to methoxy protected (-)-Δ8-THC and cholesterol. The protodeboronation was further used in the formal total synthesis of δ-(R)-coniceine and indolizidine 209B.
- Clausen, Florian,Kischkewitz, Marvin,Bergander, Klaus,Studer, Armido
-
p. 6210 - 6214
(2019/06/27)
-
- 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
-
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.
- Eisch, John J.,Galle, James E.
-
p. 293 - 314
(2007/10/02)
-
- REACTIONS OF TRIS(TRIMETHYLSILYL)METHYLSILICON COMPOUNDS WITH ORGANOLITHIUM REAGENTS
-
The compounds TsiSiH3, TsiSiH2F, and TsiSiH2I (Tsi = (Me3Si)3C) have been shown to react with p-YC6H4Li (Y = H, Me, MeO, Cl, or CF3) compounds in ether/hexane to give the corresponding compounds TsiSiH2(C6H4Y); use of TsiSiH2F gives the best results.When
- Azarian, Davoud B.,Eaborn, Colin,Lickiss, Paul D.
-
-