41719-63-5Relevant academic research and scientific papers
Lithiated camphor-derived oxazolidinone S,N-acetals as chiral formyl anion synthons in additions to aldehydes. Asymmetric synthesis of α-hydroxy aldehydes and α-hydroxy acids
Gawley, Robert E.,Campagna, Silvio A.,Santiago, Marcelina,Ren, Tong
, p. 29 - 36 (2007/10/03)
N-(Phenylthiomethyl)oxazolidinones derived from camphor can be lithiated and added to aldehydes in good yields and stereoselectivities. The adducts are crystalline, which simplifies isolation of the major diastereomer from the product mixture. Hydrolysis affords enantiopure α-hydroxy aldehydes, which can be oxidized to α-hydroxy acids in good yields. The steric course of the reaction is analyzed in detail and a mechanistic model is presented.
Asymmetric aldol reactions. A new camphor-derived chiral auxiliary giving highly stereoselective aldol reactions of both lithium and titanium(IV) enolates
Bonner, Mary Pat,Thornton, Edward R.
, p. 1299 - 1308 (2007/10/02)
A new, conformationally rigid camphor-derived N-propionyloxazolidinone effects asymmetric stereochemical control in syn-selective aldol condensations of the derived lithium and titanium(IV) enolates with a variety of aldehydes. Simple and diastereofacial selectivities of the reaction are high, and diastereomeric purities of the crude aldol adducts can be improved, usually by a single recrystallization, to levels of 98-99% in most cases. The observed facial selectivity is best explained by a transition structure in which intramolecular chelation between the oxazolidinone carbonyl oxygen and the metal induces an enolate π-facial differentiation; the major products observed are those expected from chelation control. Hydrolysis of the exocyclic carbonyl of the aldol adducts led to β-hydroxy-α-methylcarboxylic acids, with recovery of the chiral auxiliary. Consonant double-asymmetric induction with (R)-2-(benzyloxy)propanal gave the product expected from oxazolidinone chelation but nonchelation of the aldehyde benzyloxy group.
