Synthesis of novel hybrid 1,5-disusbtituted 1H-tetrazol-5yl 4,5-dihydro [1,2,3]triazolo[1,5-a]pyrazin-6-ones via high-order MCR-S_N2/intramolecular [3 + 2] cycloaddition sequence

The Semi-Synthesis of Imidazo-5α-Hydroxyvouacapane from Caesalpinia pulcherrima via a Groebke–Blackburn–Bienaymé Reaction

“…Colorless crystals; m.p. 98-100 °C; 1 H-NMR (400 MHz, CDCl3): δ 7.21 (d, J = 1.1 Hz, 1H), 6.18 (d, J = 1.6 Hz, 1H), 2.58 (dd, J = 6.8, 4.1 Hz, 1H), 2.49-2.43 (m, 1H), 2.37-2.35 (m, 1H), In continuation of our studies of natural product derivatives and the synthesis of biologically relevant compounds by using I-MCR such as Ugi-azide and the Groebke-Blackburn-Bienaymé reaction (GBB) [13][14][15][16], herein, we report the isolation of 5α-hydroxyvouacapane 5 and the semi-synthesis of imidazo-5α-hydroxyvouacapane through the GBB reaction.…”

“…Thin-layer chromatography (TLC) was performed with silica gel plates from Merck (silica gel 60 F 254), and a mixture of hexanes-EtOAc was used as eluent. The NMR spectra were recorded at 400 MHz for 1 H and 100 MHz for 13 C on a Varian Mercury 400 spectrometer (Varian, Palo Alto, CA, USA), using CDCl 3 as the solvent and TMS as the internal standard. The chemical shift (δ) is reported in ppm, and the J values are given in Hertz.…”

“…Isovouacapenol C 1 [10], pulcherrimin C 2 [11], pulcherrimin A 3 [12], 8,9,11,14-didehydrovouacapen-5α-ol 4, and 5α-hydroxyvouacapane 5 [10] are some of the metabolites isolated in this species, the latter being the natural product under study in this work (Figure 1). In continuation of our studies of natural product derivatives and the synthesis of biologically relevant compounds by using I-MCR such as Ugi-azide and the Groebke-Blackburn-Bienaymé reaction (GBB) [13][14][15][16], herein, we report the isolation of 5α-hydroxyvouacapane 5 and the semi-synthesis of imidazo-5α-hydroxyvouacapane through the GBB reaction.…”

Isocyanide–Based Multicomponent Reactions Coupled One–Pot Process: Efficient Tools to Diversity–Oriented Synthesis of Structural Peptidomimetics

“…The UA/post–transformation coupled with eco–friendly IAAC at room temperature for the synthesis of complex 1,5‐DS−T is unreported. It is highlighted that the synthesis of 1,5‐DS−T linked to CCP or anchored that includes the construction of three different heterocycles through IMCR‐based strategies is few reported [27,28] . The incorporation of a heterocyclic substituent linked at the N ‐1 α‐carbon position of the pyrazinone ring allowed an increase in the CCP complexity.…”

Late‐stage functionalization of Vouacapane derivatives from Caesalpinia platyloba by a Groebke−Blackburn−Bienaymé reaction

“…[16][17][18] To our delight, the 6β-acetoxyvouacapane 9 or their derivatives have not been used as starting reagents in multicomponent reactions. Therefore, since there are only two reports describing the use of natural products or their derivatives in the GBB reaction, and in continuation with our research program on the synthesis of biologically relevant compounds via I-MCRs, [19][20][21][22] we describe here a late-stage functionalization of a small series of fused Vouacapane-azoles 11a-f via the GBB reaction (Scheme 1C).…”