- Asymmetric Synthesis of Indoline from Achiral Phthalimide Involving Crystallization-Induced Deracemization
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Asymmetric synthesis was performed by combining the photochemical reaction of an achiral substrate followed by crystallization-induced deracemization. The results indicated that a fused indoline produced by photochemical intramolecular δ-hydrogen abstraction and cyclization of N-(5-chloro-2-methylphenyl)phthalimide crystallized as a racemic conglomerate. Since this substrate has an aminal skeleton, racemization involving a ring-opening and ring-closing equilibrium process occurred under suitable conditions. Efficient racemization was observed in acetone containing a catalytic base, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Crystallization-induced dynamic deracemization by Viedma ripening from racemic indoline was performed with an excellent enantioselectivity of 99 % ee. Furthermore, one-pot asymmetric synthesis of the indoline was achieved by the photochemical reaction of achiral phthalimide followed by continuous attrition-enhanced deracemization converging to 99 % ee of enantiomeric crystals. This is the first example of asymmetric expression and amplification by photochemical hydrogen abstraction and crystallization-induced dynamic deracemization.
- Nakamura, Takumi,Ban, Kazuma,Yoshida, Yasushi,Mino, Takashi,Kasashima, Yoshio,Sakamoto, Masami
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supporting information
p. 16338 - 16341
(2021/10/12)
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- Synthesis and?biological activity of?6H-isoindolo[2,1-a]indol-6-ones, analogues of?batracylin, and?related compounds
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Closely related to batracylin, 6H-isoindolo[2,1-a]indol-6-ones including 2-nitro- 13a, 2-amino- 14, and 2-diethylaminopropionamide derivative 16 as well as D-ring substituted 13b, 13c or A-ring substituted 13d and 20 analogues, were synthesised and evaluated against L1210 leukaemia. Subsequent treatment of 13b and 13c with N,N-diethylethylenediamine at 180?°C, led to compounds 17a and 17b arising from an unexpected opening of the pyrrolidinone ring and amidification of the keto group. Under the same conditions, the dichloro derivative 13d led to the monoalkyl compound 20 which was the most cytotoxic of the series.
- Guillaumel, Jean,Léonce, Stéphane,Pierré, Alain,Renard, Pierre,Pfeiffer, Bruno,Arimondo, Paola B.,Monneret, Claude
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p. 379 - 386
(2007/10/03)
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