4362-18-9Relevant articles and documents
Combination of NH2OH·HCl and NaIO4: an effective reagent for molecular iodine-free regioselective 1,2-difunctionalization of olefins and easy access of terminal acetals
Chakraborty, Nirnita,Santra, Sougata,Kundu, Shrishnu Kumar,Hajra, Alakananda,Zyryanov, Grigory V.,Majee, Adinath
, p. 56780 - 56788 (2015/07/15)
We have demonstrated a new application of our oxidizing reagent, a combination of NH2OH·HCl and NaIO4, in the first generalized regioselective 1,2-difunctionalization of olefins. It is a general method for the preparation of β-iodo-β′-hydroxy ethers, β-iodo ethers, β-iodohydrin, and β-iodo acetoxy compounds using different reaction media. The reactions are highly regioselective, always affording Markovnikov's type addition products. The methodology is also applicable for the easy access of terminal acetals. Molecular iodine-free synthesis, room temperature reaction conditions, high yields, use of less expensive reagents, mild reaction conditions, broad applicability of nucleophiles, and applicability for gram-scale synthesis are the notable advantages of this present protocol.
Palladium(II)-Catalyzed Acetalization of Terminal Olefins Bearing Electron-Withdrawing Substituents with Optically Active Diols
Hosokawa, Takahiro,Ohta, Toshiyuki,Kanayama, Satoshi,Murahashi, Shun-Ichi
, p. 1758 - 1764 (2007/10/02)
Terminal olefins bearing electron-withdrawing substituents such as CH2=CHCOR (R=Ph, Me, t-Bu), CH2=CHCOOMe, and CH2=CHCN are regioselectively acetalized at the terminal carbon (C1) by diols in the presence of PdCl2 (0.1 equiv) and CuCl (1 equiv) in DME at 50 deg C under an atmosphere of O2 (1 atm).The use of optically active (R,R)-2,4-pentanediol (4) gives homochiral cyclic acetals of aldehyde precursors in good yields.The acetalization of CH2=CHCOR is accompanied by the formation of Michael-type adducts such as 3a (R=Ph).However, of importance is that their formation can be prevented by the use of Na2HPO4 as an additive.Although in an early stage of the reaction of CD2=CHPh with 4, a statistical d scrambling of the starting olefin occurs, no such scrambling is observed with CD2=CHCOPh.Additionally, the acetalization of CD2=CHCOPh with 4 results in 1,2 deuterium migration, together with 25percent d loss.These results are accounted for by the reaction pathways involving oxypalladation, Pd-H elimination, and subsequent ring closure giving enol ether.A catalytic cycle involving the oxygenation of Pd-H species with molecular oxygen is proposed.
REACTIONS DE TRANSCETALISATION-III. APPROCHE QUANTITATIVE DE LA SELECTIVITE ET DU RENDEMENT POUR LES MOLECULES DIFONCTIONNELLES.
Bauduin, G.,Bondon, D.,Pietrasanta, Y.,Pucci, B.
, p. 245 - 254 (2007/10/02)
Evidence for an intramolecular transketalization equilibrium in a polyfunctional molecule is described.Using thermodynamic rules, it is possible to establish mathematical equations linking yields with relative ketalization energies and excess of reagent.Experiments with simple compounds are in good agreement with the results obtained from the mathematical model.Thus, for any bifunctional molecule, one can calculate the relative ketalization energy of each function from a simple experiment, and then determine the nature and the excess of the reagent which are necessary to realize the transketalization reaction in the best conditions of yield or selectivity.