88307-34-0Relevant academic research and scientific papers
Carbohydrate-auxiliary assisted preparation of enantiopure 1,2-oxazine derivatives and aminopolyols
Jasinski, Marcin,Lentz, Dieter,Reissig, Hans-Ulrich
supporting information; experimental part, p. 662 - 674 (2012/06/16)
An approach to enantiopure hydroxylated 2H-1,2-oxazine derivatives is presented utilizing the [3 + 3] cyclisation of lithiated alkoxyallenes and an L-erythrose-derived N-glycosyl nitrone as precursors. This key step proceeded only with moderate diastereoselectivity, but allowed entry into both enantiomeric series of the resulting 3,6-dihydro-2H-1,2-oxazines. Their enol ether double bond was then subjected to a hydroboration followed by an oxidative work-up, and finally the auxiliary was removed. The described three-step procedure enabled the synthesis of enantiopure hydroxylated 1,2-oxazines. Typical examples were treated with samarium diiodide leading to enantiopure acyclic aminopolyols. We also report on our attempts to convert these compounds into enantiopure hydroxylated pyrrolidine derivatives.
Electronic and Conformational Effects in the Photochemistry of α-Alkenyl-Substituted Vinyl Halides
Krijnen, Erik S.,Zuilhof, Han,Lodder, Gerrit
, p. 8139 - 8150 (2007/10/02)
The photochemical reactions in methanol of the vinylic halides 2-halo-1-phenyl-1,3-butadienes 1-3Z-X (β-halo-β-alkenylstyrenes) and 1-halo-1,2-diphenylethenes 4Z-X (α-halostilbenes), with X = Cl or Br, have been studied quantitatively.E/Z isomerization, dehydrohalogenation, nucleophilic substitution, a -halogen shift, a -hydrogen shift, and oxidation are observed as the primary reactions.No reductive dehalogenation products are formed.The efficiencies of product formation are dependent on the halogen used, the electron-donating capacity of the α-substituent, the ground state conformation of the starting material, and the wavelength of excitation.Apart from the photoinduced E/Z isomerization and the oxidation reaction typical for alkenes, product formation occurs exclusively via vinyl-cationic intermediates, which are formed upon photolytic cleavage of the carbon-halogen bond.These ionic species, or part of them, are present as vinyl cation/halide anion-pairs.
Titanium as a Regio- and Stereo-selective Control Element in the Reaction of α-Alkoxyallylic Phosphine Oxide Anions with Carbonyl Compounds
Birse, Ewan F.,McKenzie, Alexander,Murray, Alistair W.
, p. 1039 - 1046 (2007/10/02)
A general method is described for directing the condensation of α-methoxyallylphosphine oxide anions (2) with aldehydes, preferentially at the α-position of the allyl system.The procedure, which employs the formation of the titanium ate complex, yields pure diastereoisomers with high stereoselectivity, and these can be used in Horner-Wittig reactions to provide an efficient and convenient synthesis of conjugated methoxydienes of defined geometry.Under the same conditions, acyl halides yield γ-adducts.
A NEW ELONGATION REACTION OF THREE CARBON UNITS
Murai, Akio,Abiko, Atsushi,Shimada, Naoki,Masamune, Tadashi
, p. 4951 - 4954 (2007/10/02)
A new modification of Peterson reaction leading to elongation of three carbon units by treatment of aldehydes with titanium ate complex, prepared from 1-lithio-1-(1-alkoxy)allyltrimethylsilane and titanium(IV) isopropoxide, is described.
PREPARATION OF E-1-SUBSTITUTED-2-METHOXYBUTADIENES FROM METHOXYALLENE
Kucerovy, Andrew,Neuenschwander, Kent,Weinreb, Steven M.
, p. 875 - 880 (2007/10/02)
The title dienes have been efficiently prepared by a two-step sequence involving initial alkylation of the carbanion derived from methoxyallene followed by isomerization to the 1,3-diene with pyridinium p-toluenesulfonate.
