SbCl5–wet acetonitrile: a new system for chemoselective O-desilylation
摘要:
A new efficient method for deprotection of TBDMS derivatives of phenols, primary alcohols, carboxylic acids and secondary amines, consisting of SbCl5 and MeCN with 0.1% water (w/v), is reported. It effects inter alia desilylation of a CH2OTBDMS group in the presence of a ketal function. (C) 2003 Elsevier Ltd. All rights reserved.
1,8-diazabicyclo[5.4.0]undec-7-ene (dbu): An effective base for the introduction of tbutyldimethylsilyl group in organic compounds.
作者:Jesus M. Aizpurua、Claudio Palomo
DOI:10.1016/s0040-4039(00)61915-9
日期:1985.1
Reaction of alcohols, thiols, amines, carboxylic acids, phenols, hydroquinones, ketoesters and amides with equimolecular amounts of t-butyldimethylchlorosilane and DBU, even in solvents other than dimethylformamide affords the corresponding t-butyldimethylsilyl derivatives in high yield.
Reaction of -silyl imines with silyi keteneacetals in the presence of ZnI2 and t-butyl alcohol, followed by treatment of the intermediate -silyl β-aminoesters with MeMgBr, produces -silyl-azetidin-2-ones in good yield; use of trimethylsilyl triflate as Lewis acid catalyst can be advantageous in some cases. The preparation of the -t-butyldimethylsilyl imine of ethyl glyoxylate in this context is detailed
Lithium n-benzyltrimethylsilylamide (LSA): a new reagent for conjugate addition - enolate trapping reactions
作者:Naoki Asao、Tadao Uyehara、Yoshinori Yamamoto
DOI:10.1016/s0040-4020(01)86664-3
日期:1988.1
4-manner, though the reaction of ordinary lithium amides with α,β-unsaturated carbonyl compounds is accompanied with a 1,2-addition and hydrogen abstraction at the γ-position. The conjugateaddition via LSA followed by enolate trapping with electrophiles produces the corresponding α-substituted β-amino esters, which are, in turn, converted into β-lactams and α-substituted α, β-unsaturated esters.
The active complexes of chiral N,N′‐dioxide ligands with dysprosium and magnesium salts catalyze the hetero‐Diels–Alderreaction between 2‐aza‐3‐silyloxy‐butadienes and alkylidene oxindoles to selectively form 3,3′‐ and 3,4′‐piperidinoyl spirooxindoles, respectively, in very high yields and with excellent enantioselectivities. The exo‐selective asymmetric cycloaddition successfully regaled the construction
(4+3) Annulation of Donor‐Acceptor Cyclopropanes and Azadienes: Highly Stereoselective Synthesis of Azepanones
作者:Stefano Nicolai、Jérôme Waser
DOI:10.1002/anie.202209006
日期:2022.9.5
Azepanones are important and widespread seven-membered heterocycles, but their synthesis is challenging. A convergent method to access these scaffolds was developed relying on a (4+3) annulation reaction of azadienes and donor-acceptor cyclopropanes. Good to excellent yields and high diastereoselectivity were achieved using Yb(OTf)3 as the catalyst. Asymmetric induction was possible with Cu(OTf)2 in