Pd(0)-catalyzed regio- and stereoselective cyclization of alkynes: selective synthesis of (E)-4-(isobenzofuran-1(3H)-ylidene)-1,2,3,4-tetrahydroisoquinolines and aze/oxepinoindoles

Abstract

Palladium-catalyzed highly regio- and stereoselective 6-exo-dig and 7-endo-dig cyclization of functionalized propargylic compounds has been developed for the synthesis of (E)-4-(isobenzofuran-1(3H)-ylidene)-1,2,3,4-tetrahydroisoquinolines and aze/oxepinoindoles.

Synthesis of tetra-substituted olefins via annulation by Pd-catalyzed carbopalladation/C–H activation and solid state fluorescence properties

“…K 2 CO 3 in DMF as a solvent at 100 C under N 2 . The structure of product 3a was deduced from 1 H, 13 C NMR and HRMS analysis. Furthermore, the connectivity and molecular structure of cyclic compounds were unambiguously conrmed by single crystal X-ray analysis of compound 3a (Fig.…”

“…Melting points were determined in capillary tubes and are uncorrected. 1 H NMR (400 MHz) and 13 C (100 MHz) spectra were recorded in CDCl 3 solution with TMS as an internal standard on a Bruker Avance III HD spectrometer. High resolution mass spectra (HRMS-ESI) were recorded using a Thermo Scientic Exactive Orbitrap mass spectrometer.…”

“…1 H NMR (400 MHz, CDCl 3 ) d 7.64-7.62 (m, 2H), 7.58 (d, J ¼ 7.5 Hz, 2H), 7.42-7.37 (m, 5H), 7.30 (t, J ¼ 7.2 Hz, 2H), 7.25-7.21 (m, 1H), 7. 16-7.13 (m, 3H), 6.95 (s, 1H), 4.91 (s, 1H), 3.92-3.88 (m, 4H), 3.83 (s, 3H), 3.79 (d, J ¼ 13.5 Hz, 1H), 3.63 (d, J ¼ 5.6 Hz, 1H), 3.59 (d, J ¼ 6.2 Hz, 1H), 2.33 (s, 3H) ppm; 13 C NMR (100 MHz, CDCl 3 ) d 148. 5, 148.5, 139.6, 137.3, 136.1, 132.1, 130.7, 129.1, 129.0, 128.5, 128.4, 128.4, 128.3, 127.2, 123.5, 115.3, 114.4, 113.4, 88.6, 85.2, 56.3, 56.3, 56.1, 55.0, 53.6, 21.2 ppm.…”

“…Yield: 78%, colourless liquid. 1 H NMR (400 MHz, CDCl 3 ) d 7.85 (dd, J ¼ 5.1, 3.9 Hz, 1H), 7.65-7.63 (m, 2H), 7.40-7.38 (m, 3H), 7.28-7.25 (m, 5H), 7.18-7.15 (m, 2H), 7.10 (dd, J ¼ 5.4, 3.5 Hz, 1H), 6.93 (s, 1H), 6.80 (s, 1H), 5.03 (s, 1H), 3.83 (s, 3H), 3.82 (d, J ¼ 3.0 Hz, 1H), 3.79 (d, J ¼ 3.5 Hz, 1H), 3.77 (s, 3H), 3.70 (d, J ¼ 13.6 Hz, 1H), 3.59 (d, J ¼ 12.8 Hz, 1H), 2.10 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) d 148. 4, 148.1, 138.7, 137.5, 136.3, 131.9, 130.6, 130.5, 129.9, 129.8, 128.4, 128.2, 128.0, 127.9, 127.2, 125.4, 123.4, 115.0, 114.6, 114.0, 88.9, 85.4, 56.1, 55.7, 55.6, 54.8, 53.7, 19.0 ppm.…”

“…Previously, we described the synthesis of tetra-substituted olen based xanthene derivatives via palladium catalyzed intramolecular carbocyclization of substituted 2-bromobenzyl-N-propargylamines and their photophysical properties in both solid and aggregation states. 13 As part of our ongoing efforts on the palladium catalyzed formation of tetra-substituted alkenes through cascade reactions, 14 herein we report the palladiumcatalyzed intermolecular annulation of 2-bromo-N-benzylpropargylamines with norbornene towards the formation of tetrasubstituted helical olen incorporated 1,2,3,4-tetrahydroisoquinoline and methanouoren-9-ylidene (Scheme 1). In this domino process, suitably positioned internal aryl bromides trigger initiation of the cyclization, leading to the formation of one C(sp 2 )-C(sp 2 ) and two C(sp 3 )-C(sp 2 ) bonds, resulting in simultaneous creation of highly crowded tetra-substituted helical olens.…”