The BF3 and B(C6F5)3-catalyzed 1,3-isomerization of allylic stannanes
摘要:
A spectroscopic and chemical study of the stereospecific B(C6F5)(3)-catalyzed 1,3-isomerization of (E,S)-1-methoxymethoxy-2-butenyl tributylstannane to (Z,S)-1-methyl-3-methoxymethoxy-2-propenyl tributylstannane is described. A pathway involving an intermediate B(C6F5)(3) adduct is proposed based upon H-1- and Sn-119-NMR data. Analogous spectral evidence was not observed in the seemingly related BF3. OEt2-catalyzed isomerization. However, the similar product ratios obtained in B(C6F5)(3) and BF3. OEt2-promoted additions of the latter stannane to o- and p-methoxybenzaldehyde reveals a close similarity between the two and prompts speculation that the BF3. OEt2-catalyzed 1,3-isomerization proceeds by an analogous pathway. A pathway for the B(C6F5)(3)-promoted addition of allylic stannanes to o-methoxybenzaldehyde is also presented. (C) 2001 Elsevier Science B.V. All rights reserved.
Synthesis of Chiral α,δ-Dioxygenated Allylic Stannanes as Reagents for Carbohydrate Synthesis and Homologation
作者:James A. Marshall、Albert W. Garofalo
DOI:10.1021/jo961671b
日期:1996.1.1
delta-oxygenated allylicstannanes 4.4 and 4.5, prepared through addition of Bu(3)SnLi to gamma-OTBS crotonaldehyde 4.3c followed by etherification of the adduct with TBS-Cl or MOM-Cl, undergo transmetalation with InCl(3) and in situ addition to aldehydes leading to mainly anti adducts 5.1 or 5.2, accompanied by varying amounts of syn diastereomers. Selectivities of >95:5 can be realized with the MOM reagent 4.5
Three-Component Synthesis of Homoallylic Amines Promoted by Carboxylic Acids
作者:Gang Zhao、Gui-long Li
DOI:10.1055/s-2006-942548
日期:——
A highly selective, three-component reaction promoted by carboxylic acids for the synthesis of homoallylicamines has been developed. By using maleic acid or trifluoroacetic acid as a promoter, the reaction between a variety of aldehydes, aromatic amines, and allyltin reagents proceeds smoothly to afford the corresponding homoallylicamines in moderate to quantitative yields under mild conditions.
Highly stereoselective synthesis of vicinal diols by stannous chloride-mediated addition of hydroxyallylic stannanes to aldehydes
作者:Makoto Yasuda、Tatsuya Azuma、Kensuke Tsuruwa、Srinivasarao Arulananda Babu、Akio Baba
DOI:10.1016/j.tetlet.2009.01.137
日期:2009.7
A new protocol for the synthesis of vicinaldiols was accomplished by the reaction of unprotected α-hydroxymethylmetals, as hydroxymethyl anion equivalents, with aldehydes. The treatment of hydroxyallylic stannanes, which were prepared from α,β-unsaturated aldehydes and Bu3SnLi in situ, with various aldehydes gave but-3-en-1,2-diols in the presence of SnCl2. The stereochemistry of the diol and olefin
On the use of E-1-methoxymethoxybut-2-enyl(tri-n-butyl)stannane as a threo-selective, homo-enolate equivalent
作者:Andrew J. Pratt、Eric J. Thomas
DOI:10.1039/c39820001115
日期:——
(E)-1-Methoxymethoxybut-2-enyl(tri-n-butyl)stannane, readily available by addition of tri-n-butylstannyllithium to crotonaldehyde, and protection of the alcohol so formed using chloromethyl methyl ether, reacts on heating with aromatic and aliphatic aldehydes to give threo-4,5-disubstituted butyrolactones.