- Enantioselective organocatalytic conjugate addition of aldehydes to vinyl sulfones and vinyl phosphonates as challenging michael acceptors
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Chiral amines with a pyrrolidine framework catalyze the enantioselective conjugate addition of a broad range of aldehydes to various vinyl sulfones and vinyl phosphonates in high yields and with enantioselectivities up to >99% ee. This novel process provides synthetically useful chiral γ-gem-sulfonyl or phosphonyl aldehydes which can be widely functionalized with retention of the enantiomeric excess. Mechanistic insights including DFT calculations are explored in detail.
- Sulzer-Mosse, Sarah,Alexakis, Alexandre,Mareda, Jiri,Bollot, Guillaume,Bernardinelli, Gerald,Filinchuk, Yaroslav
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supporting information; experimental part
p. 3204 - 3220
(2009/12/03)
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- Improved preparation of diethyl bromomethylphosphonate and diiodomethane-catalyzed triethylphosphite Michaelis-Arbuzov isomerization
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An improved method to prepare diethyl bromomethylphosphonate and a new method for the isomerization of triethyl phosphite into diethyl ethylphosphonate are reported.
- Ezquerra,Yruretagoyena,Moreno-Manas,Roglans
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p. 191 - 194
(2007/10/02)
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- Free radical reaction of α-haloalkylphosphonates with alkenes and alkynes: A new approach to modified phosphonates
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A new approach to the synthesis of phosphonates 3 functionalized in the α- and γ-phosphonate positions by alkyl, ethoxy, butoxy, acetoxy, acetyl and cyanide groups and allylphosphonate 6 is described. It is based on the radical reaction of α-halosubstituted phosphonates 1 (X = Cl, Br, I) with the terminally unsubstituted alkenes 2 (1-heptene, ethoxyethene, butoxyethene, acetoxyethene, acrylonitrile, methyl vinyl ketone) and alkyne 5 (hept-1-yne). The reaction involving the tin hydride method (Bu3SnH/AIBN) was more effective with alkenes than with alkynes (40-72% versus 20-30%). With electron-rich alkenes, chloro- and bromomethylphosphonates 1 (X = Cl, Br) gave higher yields than iodomethylphosphonate 1 (X = I). Diethyl methylphosphonate 4, as a reduction product of 1, accompanied 3 and 6 in the above reactions. The yield of 4 could be reduced by optimizing the reaction conditions.
- Balczewski,Mikolajczyk
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p. 392 - 396
(2007/10/02)
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- α-Substituted Phosphonates. 39. Methane-diphosphonic Esters by U.V.-Induced Michaelis-Becker-Reaction
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Dibromomethane resp. chlorbromomethane reacts with sodium dialkyl phosphite in heptane-/liq.NH3 or in liq.NH3 by u.v. irradiation at low temperatures to give in good yields methane diphosphonic acid tetraalkylesters 1.In the same manner with sodium diethyl thionophosphite the corresponding methane-bisthiophosphonic acid tetraethylester 4 is obtained.
- Czekanski, T.,Gross, H.,Costisella, B.
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p. 537 - 544
(2007/10/02)
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