thiazoline-2-thione and 3-hydroxybutanal

Synthesis of the C1-C6 and C7-C23 fragments of the proposed structure of iriomoteolide 1a has been accomplished. Key steps include a cross metathesis to form the C15-C16 E olefin and a chelation controlled Grignard addition to form the tertiary alcohol at C14. Notably, 7 of the 9 stereocenters of the proposed structure have been set using various aldol reactions employing metallo enolates of thiazolidinethiones.

Topics: Aldehydes; Macrolides; Molecular Structure; Stereoisomerism; Thiazolidines

An indene-based thiazolidinethione chiral auxiliary was prepared in two steps from trans-1-amino-2-indanol. Chlorotitanium enolates of this chiral auxiliary delivered excellent diastereoselectivities in propionate and acetate aldol additions. The chiral auxiliary was easily removed to deliver several valuable functionalities.

Topics: Acetates; Aldehydes; Indans; Indenes; Molecular Structure; Propionates; Stereoisomerism; Thiazolidines

A highly convergent formal synthesis of the auriside aglycon was achieved. An indene-based thiazolidinethione chiral auxiliary was used for the construction of both the C1-C9 and C10-C17 fragments via acetate aldol reactions. A Meinwald reaction was utilized to install the stereocenter at C2, and a conjugated addition to an ynone was used to construct the C9-C11 enone.

Topics: Acetates; Aldehydes; Macrolides; Stereoisomerism; Thiazolidines

[reaction: see text] Highly diastereoselective acetate aldol additions using chlorotitanium enolates of mesityl-substituted N-acetyloxazolidinethione and N-acetylthiazolidinethione auxiliaries are reported. These additions proceed in high yields and diastereoselectivities (93:7 to 98:2) for aliphatic, aromatic, and ,-unsaturated aldehydes. Double diastereoselective acetate aldol additions are also reported and are found to proceed in high yields and diastereoselectivities (90:10 to 97:3).

Topics: Acetates; Aldehydes; Chromatography, High Pressure Liquid; Molecular Structure; Oxazolidinones; Stereoisomerism; Thiazolidines

The synthesis of (-)-stemoamide was achieved in 11 steps from 5-acetoxy-N-crotyl pyrrolidinone. A chiral N-acyl thiazolidinethione was employed in a stereoselective addition to a cyclic N-acyl iminium ion to install the required stereochemistry of carbon C9a. This iminium ion addition product was employed in a stereoselective MgBr2-catalyzed anti-aldol reaction to install the required stereochemistry of carbons C8 and C9. The X-ray crystal analysis of (-)-stemoamide confirmed the structure and the stereochemical outcome of these selective reactions.

Topics: Aldehydes; Alkaloids; Azepines; Crystallography, X-Ray; Heterocyclic Compounds, 3-Ring; Lactones; Molecular Structure; Stereoisomerism; Thiazolidines

Double diastereoselective acetate aldol reactions using the N-acetyl thiazolidinethione-based chiral auxiliaries 1 and 2 and chiral aldehydes are described. Aldehydes that bear alpha-alkyl stereocenters exhibit moderate levels of double diastereoselection, while those that bear alpha- or beta-alkoxy substitution exhibit little to no double diastereoselection. In all cases studied, the stereoselectivity of the reaction is dictated by the reagent, not the substrate.

Topics: Acetates; Aldehydes; Hydrogenation; Imines; Molecular Structure; Stereoisomerism; Thiazolidines