Direct conversion of chiral cyanohydrins to chiral nitrones by transimination

α-Fluoroacrylonitriles: Horner–Wittig synthesis and conversion into 2-fluoroallylamines and C-(1-fluorovinyl)nitrones

“…Though yields were not as high as found for O-protected cyanohydrins [19][20][21][22][23], the reactions show that a-fluoroacrylonitriles 2 can be conveniently derivatized through the transimination procedure. 2 Reaction of primary imines 5 with N-benzylhydroxylamine [29] yielded novel C-(1-fluorovinyl)nitrones 8 (Scheme 3). They were obtained, usually in high yields, as colorless solids.…”

Intramolecular Cycloaddition Reactions of ω-Unsaturated Chiral Nitrones

“…Then dry methanol was added to liberate the free imine and destroy the excess of DIBAL. Subsequent addition of N-benzylhydroxylamine initiated the transimination reaction [2] (Scheme 1). When protected cyanohydrin 2a was used as the starting material the bicyclic cycloaddition product was obtained directly instead of the expected nitrone.…”

“…Recently, a one-pot procedure duction of the NϪO bond, to produce both an amino and was published for the synthesis of chiral aldo and keto a hydroxy function, allows the synthesis of tailor-made nitrones by way of a transimination-based reaction se-products of possible biological interest [1a] . quence, starting from O-protected chiral α-hydroxynitriles When both alkene and nitrone functionality are com-(cyanohydrins) [2] (Scheme 1). Cyanohydrins can be pre-bined in one molecule, intramolecular 1,3-dipolar cycloadpared in excellent enantiomeric purity by asymmetric ad-dition can occur and numerous examples of the application dition of hydrogen cyanide to aldehydes in a reaction cata-of this principle have been published [1a] [6] [7] .…”

Synthesis of Eight 1‐Deoxynojirimycin Isomers from a Single Chiral Cyanohydrin

“…[5] For example, (2R,3E)-2-hydroxypent-3-enenitrile (1), derived from crotonaldehyde and HCN can be prepared in 99 % enantiomeric purity by using either purified paHNL [6] or defatted almond meal containing the enzyme (Scheme 1). [10] The protected forms can be used to produce chiral nitrones, [11] cyclic 1,2-ethanolamines, [12] chiral piperidinols, [12] α-hydroxy-β-amino acids, [13] tetronic acids [14] and 1,2-ethanolamines. In the unprotected form it has been used in the synthesis of α-hydroxy esters, [8] α-hydroxy acids [9] and vicinal diols.…”

“…In the unprotected form it has been used in the synthesis of α-hydroxy esters, [8] α-hydroxy acids [9] and vicinal diols. [10] The protected forms can be used to produce chiral nitrones, [11] cyclic 1,2-ethanolamines, [12] chiral piperidinols, [12] α-hydroxy-β-amino acids, [13] tetronic acids [14] and 1,2-ethanolamines. [15] Scheme 1.…”