Masahiro Koga

Three-component coupling synthesis of prostaglandins. A simplified, general procedure

Abstract In the presence of dimethylzinc, ( R)-tert -butyldimethylsiloxy-2-cyclopentenone can be linked with ( S,E )-1-lithio-3- tert -butyldimethylsiloxy-1-octene and methyl 7-1odo-5-heptynoate, giving a protected 5,6didehydroprostaglandin E 2 - Use of an ω side-chain aldehyde or nitroalkene in place of the propargylic iodide affords the C-7 and C-6 functionalized prostaglandins, respectively. This new protocol constitutes the simplest three-component method for the synthesis of various natural and unnatural prostaglandins.

Short synthesis of isocarbacyclin by regioselective SN2′ alkylation of bicyclic allylic esters with zinc-copper reagents☆

Abstract Isocarbacyclin [(+)-9(O)-methano-Δ6(9α)-prostaglandin I1] (2) was synthesized from bicyclic synthons such as 2-phosphorylated, 2-(thio)phosphorylated, 2-tosylated, 2-methoxycarbonylated, and 2-chloro-3-methylenebicyclo[3.3,0]octanes via highly regioselective SN2′ alkylation with zinc-copper reagents 9 in excellent yields.

Synthesis of novel isocarbacyclins containing a phenylene moiety in the α-side chain☆

Abstract Synthesis of novel isocarbacyclin derivatives containing a phenylene moiety in the α-side chain has been achieved through the regioselective SN2′ substitution reaction of bicyclic allylic phosphates with ester-containing phenylic and benzylic zinc-copper reagents.

Studies on the Preparation of Isocarbacyclin Intermediates. I

Abstract Studies on the practical method for trapping enolates generated from enone with organocopper reagent have been described. Instead of carcinogenic hexamethylphosphoric triamide (HMPA), N-methyl-2-pyrrolidone (NMP) has been found to be an effective additive for trapping the enolate.