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Cerium(III) Chloride-Mediated Reactions of Sulfonamide Dianions

Cerium(III) Chloride-Mediated Reactions of Sulfonamide Dianions

David C Johnson 2nd, Theodore S Widlanski

J Org Chem. 2003 Jun 27;68(13):5300-9.

PMID: 12816492

Abstract:

Presented here is the first report on the ability of cerium(III) chloride to mediate high-yielding and, oftentimes, highly diastereoselective additions of N-benzyl-alpha, N-dilithio methanesulfonamide to aldehydes and ketones of biological importance. Smooth addition was effected to base-sensitive substrates such as Fmoc-protected alaninal, citral, 5-cholesten-3-one, uridine 5'-aldehyde, 3'-ketouridine, and 3'-ketothymidine. The reaction was chemoselective for aldehydes in the presence of nitriles. Acetoxy groups are labile and thus not suitable protecting groups for alcohols under these conditions. N-Benzyl-alpha, N-dilithio methanesulfonamide was found to be of sufficient basicity to cause enolate formation with sensitive substrates, such as 1-phenylacetone. However, the addition of cerium(III) chloride mediated the basicity of the dianion and suppressed enolate formation in these cases. Further, cerium(III) has general utility for the addition of various N-aliphatic/aromatic methanesulfonamide dianions to 3'-ketouridine.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP7790865	Cerium(III) chloride		7790-86-5	Price

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