The regioselective synthesis of 2,3-di- and 1,2,3-trisubstituted naphthalenes via Directed ortho Metalation (DoM) strategies of N,N-diethyl-O-naphthyl-2-carbamate (1) is presented. Sequential LiTMP metalation-electrophile quench and s-BuLi/TMEDA (or t-BuLi)-electrophile quench of naphthyl-2-carbamate 1 provides a general route to contiguously substituted naphthalenes (6) with full regioselectivity. Further derivatization via ipso-halodesilylation and Suzuki-Miyaura cross-coupling leads ultimately to substituted halonaphthalenes and benzonaphthopyranones (9).
The flavin-dependent monooxygenase RebC is a key enzyme in the biosynthesis of the indolocarbazole rebeccamycin. The synthesis of rebeccamycin is of great interest as it has been shown to be a natural antitumour agent. The enzyme has been recombinantly expressed in Escherichia coli and purified to homogeneity. Hanging-drop vapour diffusion in combination with microseeding was used to obtain suitable crystals for X-ray diffraction. Data were collected to 2.4 Å ; the crystals belonged to space group P2 1 , with unit-cell parameters a = 63.08, b = 77.85, c = 63.94 Å , = = 90, = 108.11 .
Directed ortho Metalation Strategies. Effective Regioselective Routes to 1,2-, 2,3-, and 1,2,3-Substituted Naphthalenes. -Directed ortho-metalation of naphthyl--2-carbamate followed by reaction with various electrophiles affords di-and trisubstituted naphthalenes with high regioselectivity. Further derivatization of product (XIV) via ipso-halodesilylation provides dihalonaphthalene (XV). A three step sequence involving Suzuki-Miyaura coupling, Fries rearrangement, and cyclization allows the conversion of product (XIV) into benzonaphthopyranones (XIX). -(GROOM, K.; HUSSAIN, S. M. S.; MORIN, J.; NILEWSKI, C.; RANTANEN, T.; SNIECKUS*, V.; Org. Lett. 16 (2014) 9, 2378-2381, http://dx.doi.org/10.1021/ol500707w ; Dep. Chem., Queen's Univ., Kingston, Ont. K7L 3N6, Can.; Eng.) -Mais 46-051
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