Abstract
Benzoquinolizidinone systems were synthesized in both enantiomeric forms from L-glutamic acid. The key chiral arylethylglutarimide intermediate was synthesized from dibenzylamino-glutamate and homoveratrylamine. Aldol reaction of the glutarimide afforded a mixture of syn and anti-aldol adducts. Subsequent regioselective hydride reduction of the glutarimide carbonyl followed by N-acyliminium ion cyclization afforded a product with opposite absolute configurations at C3 and C11b. Cope elimination of the dibenzylamino group then converted the two diastereomers into enantiomers.
Highlights
As a subfamily of tetrahydoisoquinoline, benzoquinolizidine has a fused piperidine important structural motif found in various alkaloids, either natas the third third ring
Afew fewreported reported that constructsyntheses the tricyclic benzoquinolizidinone core in a single step asymmetric employ tyrosine-based chiral starting material for diastereoselecasymmetric syntheses employ tyrosine-based chiral starting material for diastereoselecasymmetric syntheses employ tyrosine-basedcore chiral starting1)material diastereoselective tive synthesis of the tetrahydroisoquinoline
We have previously reported a diastereoselective synthesis of benzoquinolizidinone
Summary
As a subfamily of tetrahydoisoquinoline, benzoquinolizidine has a fused piperidine important structural motif found in various alkaloids, either natas the third third ring. Ring.ItItisisanan important structural motif found in various alkaloids, either ural or synthetic molecules. ManyMany of these alkaloids possess interesting biological activinatural or synthetic molecules. Bischler–Napieralski and Pictet–Spengler are common reactions in many tetrahydroisoquinoline syntheses [10,11,12]. There that construct the tricyclic benzoquinolizidinone core incascade a single step [13]. A few reported that construct the tricyclic benzoquinolizidinone core in a single step[13]. Afew fewreported reported that constructsyntheses the tricyclic benzoquinolizidinone core in a single step asymmetric employ tyrosine-based chiral starting material for diastereoselecasymmetric syntheses employ tyrosine-based chiral starting material for diastereoselecasymmetric syntheses employ tyrosine-basedcore chiral starting1)material diastereoselective tive synthesis of the tetrahydroisoquinoline An enantioselective Pictet–Spengler reaction of phoric been reported.
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