Cyclopropanation of tin-substituted acetals with olefinic alcohols via in situ transacetalization
作者:Masanobu Sugawara、Jun-ichi Yoshida
DOI:10.1016/s0040-4039(99)00035-0
日期:1999.2
Reactions of a tin-substituted acetal with olefinic alcohols in the presence of an acid resulted in facile transacetalization followed by intramolecular cyclopropanation to give the cyclized products in high yields and stereoselectivity.
Substitution of the acetoxy groups of dialkoxymethylacetates by organometallic reagents: a route to allyl-, propargyl-, homoallyl-, homopropargyl- and α-stannylacetals
The substitution of the acetoxy groups of dialkoxymethylacetates by organometallicreagents has been examined in a search for new methods of preparing functional acetals. The efficiency of the substitution of the acetoxy group is highly dependent on the nature of the organometallicreagents: soft nucleophiles with strong electrophilic assistance by the counterion are the best reagents. Allyl-, propargyl-
Stereoselective Synthesis of Stannylated Dehydropiperidines and Dehydroazepanes
作者:Alexandre Lumbroso、Vincent Coeffard、David Gatineau、Sebastian Stecko、Isabelle Beaudet、Jean-Paul Quintard、Erwan Le Grognec
DOI:10.1002/ejoc.201600903
日期:2016.10
stannylated azadienes into stannylated dienyl oxazolidinones, a ring-closingmetathesis generates dehydropiperidine or dehydroazepane; both are interesting scaffolds for the synthesis of polyfunctionnalized piperidines or azepanes. Whereas the dehydropiperidine synthesis was found to be selective regardless of the Grubbs catalyst used, we found that Grubbs II catalyst induced partial double bond isomerization
Stereospecific Cyclopropanation Reactions of Stannyl-Substituted Acetals with Alkenes via <i>γ</i>-Elimination of Tin
作者:Masanobu Sugawara、Jun-ichi Yoshida
DOI:10.1055/s-1998-1896
日期:1998.10
The reactions of stannyl substituted acetals with olefins resulted in the elimination of both the triorganostannyl group and the alkoxy group on the same carbon, and the production of the corresponding alkoxycyclopropanes in good yields. The stereospecificity of the present reaction suggests that γ-elimination of tin is very fast.
Camphor-derived 2-stannyl-N-Boc-1,3-oxazolidine: A new chiral formylanion equivalent for the asymmetric synthesis of 1,2-diols
作者:Lino Colombo、Marcello Di Giacomo、Gloria Brusotti、Ettore Milano
DOI:10.1016/0040-4039(95)00369-n
日期:1995.4
3-oxazolidine 6, prepared from the camphor-derived aminoalcohol 5, was converted to diastereomerically pure 2-acyl derivatives 8 in three steps. Reaction of these ketones with Grignard reagents at −78°C proceeded with high stereoselectivity affording tertiarycarbinols which gave 1,2-diols with >96% ee after hydrolysis and reduction of the intermediate α-hydroxy aldehydes. A new deblocking procedure of the