Synthesis of spirolactones by 1,3‐dipolar cycloadditions to methyl (S)‐3‐[(E)‐cyanomethylidene]‐2‐oxotetrahydrofuran‐5‐carboxylate |
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| Authors: | Samo Pirc Simon Re
nik Marko &#x;kof Jurij Svete Ljubo Goli
Anton Meden Branko Stanovnik |
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| Institution: | Samo Pirc,Simon Rečnik,Marko Škof,Jurij Svete,Ljubo Golič,Anton Meden,Branko Stanovnik |
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| Abstract: | Dedicated to Professor Emeritus Miha Ti?ler on the occasion of his 75th birthday Treatment of methyl (S)‐5‐(E)‐(dimethylamino)methylidene]‐2‐oxotetrahydrofuran‐5‐carboxylate ( 2 ) with potassium cyanide in acetic acid gave (S)‐5‐(E)‐cyanomethylidene]‐2‐oxotetrahydrofuran‐5‐car‐boxylate ( 3 ), which was used as chiral dipolarophile in 1,3‐dipolar cycloadditions. Reactions of 3 with diazomethane ( 4 ) and nitrile oxides 5a‐c afforded spirolactones 6–8 in 24‐34% diastereomeric excess, while with diazomethane ( 4 ) in the presence of triethylamine, methyl 3‐cyanomethyl‐2‐methoxyfuran‐5‐carboxylate ( 12 ) was obtained. |
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