Stereocontrol of palladium(II)-catalysed aza-Claisen rearrangements using a combination of 1,3-allylic strain and a solvent mediated directing effect.
نویسندگان
چکیده
The use of a non-coordinating solvent for the aza-Claisen rearrangement of delta,epsilon-disubstituted acetimidates switches on a substrate directing effect that gives excellent stereoselectivity.
منابع مشابه
Reversal of facial selectivity in a thia-Claisen rearrangement by incorporation of a vinylic bromine substituent.
Thia-Claisen rearrangements have been carried out using N-benzylpyrrolidine-2-thione and chiral allylic bromides derived from D-mannitol. Introduction of a bromine atom onto the double bond of the allylic bromide reverses the sense of diastereoselectivity in the [3,3]-sigmatropic rearrangement. Density functional theory calculations lead us to rationalise the observed selectivity in terms of a ...
متن کاملStereocontrolled synthesis of 1,5-stereogenic centers through three-carbon homologation of boronic esters.
Allylic pinacol boronic esters are stable toward 1,3-borotropic rearrangement. We developed a Pd(II)-mediated isomerization process that gives di- or trisubstituted allylic boronic esters with high E selectivity. The combination of this method with lithiation-borylation enables the synthesis of carbon chains that bear 1,5-stereogenic centers. The utility of this method has been demonstrated in ...
متن کاملKinetic and thermodynamic study of substituent effect on the Claisen rearrangement of para-substituted SI aryl ether: a Hammett study via DFT
In order to find the susceptibility of the Claisen rearrangement and next proton shift reaction of ally) aryl etherto the substiment effects in pan position, the kinetic and the:rmodynamie parameters are calculated at The33 LTP level using 6-3110. b asis set. The calculated activation energies for the rearrangements and protonshift reactions are around 3133 kcaUmol and 52.16 kcal/mol, nap.. liv...
متن کاملAcyclic 1,4-Stereocontrol via the Allylic Diazene Rearrangement: Development, Applications, and the Essential Role of Kinetic E Stereoselectivity in Tosylhydrazone Formation.
We report full details of a method for 1,3-reductive transposition of α-alkoxy-α,β-unsaturated hydrazones to provide E-alkenes with high 1,4-stereocontrol between the two respective allylic stereocenters. The process couples a chelation-controlled reduction of the hydrazone with an in situ allylic strain controlled retro-ene reaction of an allyl diazene, i.e., an allylic diazene rearrangement. ...
متن کاملMicrowave accelerated aza-Claisen rearrangement.
A study of microwave-induced and standard thermal Overman rearrangement of selected allylic trichloroacetimidates 1a-1f, 6-8 to the corresponding acetamides 2a-2f, 9-11 is reported. The microwave-assisted rearrangement of trifluoroacetimidate 13 is also described. Using this methodology, an efficient access to versatile allylic trihaloacetamides building synthons was established.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Organic & biomolecular chemistry
دوره 4 21 شماره
صفحات -
تاریخ انتشار 2006