- Substitution of HMPT by the Cyclic Urea DMPU as a Cosolvent for Highly Reactive Nucleophiles and Bases
-
The cyclic urea DMPU (N,N'-dimethyl-N,N'-propylene urea = 1,3-dimethyl-2-oxo-hexahydropyrimidine) is shown to exhibit the same effects as HMPT in oxirane-opening with Li-acetylide, in Wittig olefination, in the double deprotonation of a nitroalkane, in th
- Mukhopadhyay, Triptikumar,Seebach, Dieter
-
-
Read Online
- Quinuclidine N-oxide: A potential replacement for HMPA
-
The use of quinuclidine N-oxide as a replacement for HMPA is described.
- O'Neil, Ian A.,Lai, Justine Y. Q.,Wynn, Duncan
-
-
Read Online
- Replacement of HMPA in samarium diiodide promoted cyclizations and reactions of organolithium compounds
-
Tripyrrolidinophosphoric acid triamide (TPPA) can replace carcinogenic HMPA as a Lewis basic additive in many reactions involving samarium ketyls. In most cases, yields and selectivities of cyclizations of (het)aryl, alkenyl, and alkynyl ketones are simil
- Berndt, Mathias,Hoelemann, Alexandra,Niermann, Andre,Bentz, Christoph,Zimmer, Reinhold,Reissig, Hans-Ulrich
-
experimental part
p. 1299 - 1302
(2012/04/04)
-
- Synthesis of new chiral derivatives of N,N′-dimethylpropyleneurea (DMPU) and examination of their influence on the regio- and enantioselectivity of addition of 2-(1,3-dithianyl)lithium to cyclohex-2-en-1-one
-
The preparation of three new chiral derivatives of DMPU (N,N′-dimethylpropyleneurea) is described (Schemes 2-4); one type of derivative carries 1-phenylethyl or 1-cyclohexylethyl groups at the N-atoms of the tetrahydropyrimidin-2(1H)-one ring (2 and 4), a
- Juaristi, Eusebio,Hernandez-Rodriguez, Marcos,Lopez-Ruiz, Heraclio,Avina, Judit,Munoz-Muniz, Omar,Hayakawa, Michiya,Seebach, Dieter
-
p. 1999 - 2008
(2007/10/03)
-
- Studies on the substituted 3-aminopropan-1-ol motif of lycoctonine class norditerpenid alkaloids: A novel route to 3-hydroxymethylcyclohex-2-enone
-
Pursuing our interest in methyllcaconitine (MLA), we have designed a synthetic route to substituted ring-A of lycoctonine class norditerpenoid alkaloids. A novel synthesis of 3-hydroxymethylcyclohex-2-enone has been achieved starting from cyclohex-2-enone. Key reactions are: 1,2-addition of 1,3-dithiane followed by allylic rearrangement, 1,4-hydrocyanation, Wittig reaction and conversion into the substituted N-ethyl-3-aminopropan-1-ol motif of these neopentyl-like alcohols.
- Doisy, Xavier,Blagbrough, Ian S.,Thomas, Noel F.,Potter, Barry V. L.
-
p. 8525 - 8528
(2007/10/03)
-
- A SIMPLE SYNTHESIS OF γ-HYDROXY-α,β-UNSATURATED ALDEHYDES
-
A convenient method has been developed for the synthesis of γ-hydroxy-α,β-unsaturated aldehydes with one-carbon homologation from α,β-unsaturated ketones.
- Ranu, Brindaban C.,Sarkar, Dipak C.
-
p. 155 - 160
(2007/10/02)
-
- A Comparison of the Reactions of lithium with α,β-Unsaturated Ketones and Those of Other Acyl Anion Equivalents Containing Sulfur
-
The factors influencing the site of attack of lithium (1) with enones were investigated.Cyclohexenone (2) was chosen as a model compound, and conjugate addition occurred in THF-HMPA or DME; this mode of addition was also promoted by a potassium counterion.When the reaction was carried out with other enones, conjugate addition in THF-HMPA or DME was only observed if the β-position or the α,β-unsaturated ketone was not disubstituted. 1,4-Addition of 1 could be accomplished by preparation of the cuprate.The use of this approach was illustrated by a preparation of 4,4-dimethylcyclopent-2-en-1-one (28).For determination of the influence of DME on the regiochemical control of the addition of other sulfur-containing anions to enones, the study was extended to the anions derived from 1,3-dithian (29), bis(phenylthio)methane (30), bis(phenylthio)(trimethylsilyl)methane (35), and bis(trimethylsilyl)(phenylthio)methane (36).With these anions, DME did not promote conjugate addition to any significant extent.
- Ager, David J.,East, Michael B.
-
p. 3983 - 3992
(2007/10/02)
-
- CONJUGATE (1,4) ADDITION OF HETEROCYCLIC ACYL ANION EQUIVALENTS TO CYCLIC α-ENONES IN THE PRESENCE OF HEXAMETHYLPHOSPHORIC TRIAMIDE: A GENERAL REACTION
-
Heterocyclic dithiaorganolithium reagents react with cyclic α-enones in THF to yield only products of carbonyl (1,2) addition; in the presence of 2.0 equivalents of hexamethylphosphoric triamide, the addition proceeds to give nearly exclusively the produc
- Brown, Charles Allan,Chapa, O.,Yamaichi, A.
-
p. 187 - 189
(2007/10/02)
-