915376-33-9

Upstream product

• 501-53-1 benzyl chloroformate 
• 915376-31-7 benzyl 4-hydroxy-9H-carbazole-9-carboxylate 
• 915376-32-8 benzyl 3-bromo-4-hydroxy-9H-carbazole-9-carboxylate 
• 52602-39-8 9H-carbazol-4-ol 
• 915376-30-6 benzyl 4-{[(benzyloxy)carbonyl]oxy}-9H-carbazole-9-carboxylate 

Downstream Products

• 915376-35-1 3,4-dihydro-1H-indolo[3,2-j]phenanthridine-1,7,13(2H,12H)-trione 

Relevant academic research and scientific papers

Synthesis of a calothrixin B isomer with a novel 7H-indolo[2,3-j] phenanthridine-7,13(8H)-dione structure

Synthesis of an N-protected 2-bromo- 1H-carbazole-1,4(9H)-dione is reported for the first time. We took full advantage of the high polarization and electrophilic properties of this new compound to engage it in a regioselective hetero-Diels-Alder reaction. The resultant cycloadduct was next transformed to an isomer of the naturally occurring calothrixin B displaying a new 7H-indolo[2,3-j]phenanthridine-7,13(8H)-dione structure. Georg Thieme Verlag Stuttgart.

Concise and efficient synthesis of calothrixin B

A convergent synthesis of the naturally occurring alkaloid Calothrixin B is presented, which used a regioselective hetero-Diels-Alder reaction between a "push-pull" 2-aza-diene and a N-protected 3-bromo-9H-carbazole-1,4- dione to construct the five-ring skeleton of the molecule. Protection of the indole motif with a benzyl group was unattractive for delivery of sufficient target material because the removal of the protecting group had not been high yielding. We therefore elected to temporarily protect the indole motif with a more labile benzyloxycarbonyl group. Accordingly, the synthesis of calothrixin B proceeded in 17% overall yield over 9 steps from the commercially available 1,2,3,9-tetrahydro-4H-carbazol-4-one.