| Autor: |
Bernhard, Stefan, Kümmerer, Nadine, Urgast, Dagmar, Hack, Frederik, Ungelenk, Julia, Frank, Andrea, Schollmeyer, Dieter, Nubbemeyer, Udo |
| Předmět: |
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| Zdroj: |
Synthesis; Aug2024, Vol. 56 Issue 16, p2537-2548, 12p |
| Abstrakt: |
A seven-step ex-chiral-pool synthesis of optically active 4-alkylidenetetrahydroisoquinolines was developed. Starting from 6-bromopiperonal and (S)-serine esters, N -benzylation via reductive amination gave enantiopure N -piperonyl serine esters. Subsequent NH and OH protection delivered defined (S)-serine building blocks. The best results to achieve the conversion into the corresponding serinal were obtained via a two-step sequence of NaBH4 /LiCl reduction and subsequent TEMPO oxidation. Then, chain elongation using the Masamune–Roush variant of the Horner olefination afforded ethyl (E)-4-(N -6-bromopiperonyl)-substituted pentenoates in high yields. Intramolecular Heck cyclization employing the Herrmann–Beller catalyst enabled generation of enantiopure 4-(2-ethoxycarbonylmethylidene)tetrahydroisoquinoline building blocks in high Z -selectivity. Subsequent selected functional group transformations gave carbinols and lactones, which can be used as key intermediates in crinane alkaloid total syntheses. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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