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Synthesis of carbocyclic hydantocidins via regioselective and diastereoselective phosphine-catalyzed [3 + 2]-cycloadditions to 5-methylenehydantoins.

The Journal of organic chemistry (2005-07-30)
Tien Q Pham, Stephen G Pyne, Brian W Skelton, Allan H White
ABSTRACT

The phosphine-catalyzed [3 + 2]-cycloaddition of 5-methylenehydantoins 4 with the ylides 5, derived from addition of tributylphosphine to the 2-butynoic acid derivatives, 6a-d, gives spiro-heterocyclic products. The camphor sultam derivative 6b gives optically active products. Noteable was that the ylides derived from ethyl 2-butynoate and the 3-(2-butynoyl)-1,3-oxazolidin-2-one derivatives 6c and 6d gave spiro-heterocyclic products with reverse regioselectivities. The N,N-dibenzylprotected cycloadduct has been converted to carbocyclic hydantocidin and 6,7-diepi-carbocyclic hydantocidin.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Tributylphosphine, mixture of isomers, 97%
Sigma-Aldrich
Tri-n-butylphosphine, 99%
Sigma-Aldrich
Tributylphosphine, ≥93.5% (Tri-N-butylphosphine, GC)
Sigma-Aldrich
Tri-n-butylphosphine, 97%
Sigma-Aldrich
Tributylphosphine solution, 200 mM (in N-methyl-2-pyrrolidinone), liquid