Synthesis of new spiro compounds containing a carbamate group

Advances in the Synthesis of Benzo‐Fused Spiro Nitrogen Heterocycles: New Approaches and Modification of Old Strategies

“…Heating of compound 118 with hydrazine in ethanol gave an indolone‐pyrazole spiro‐fused heterocycle 123 ( Scheme 31). [190] Heterocycle 118 [191] also interacts with 3‐aminocrotonic acid ethyl ester, acetoacetic ester, but in this case spirocyclic compounds are not formed [192] . Analogs of compound 122 with benzyl and ethoxycarbonyl groups at indole and pyrazole nitrogen atoms, respectively, can also be obtained by reacting 3‐ethoxymethylidene, 3‐benzyloxycarbonylmethylidene, 3‐cyanomethylidene or 3‐benzylideneindoles with diethyl azodicarboxylate (EtO 2 CN=NCO 2 Et) in the presence of an equimolar amount of PPh 3 at room temperature with yields of 56–99 % [193] .…”

Preparation of spiro[indole-3,5′-isoxazoles] via Grignard conjugate addition/spirocyclization sequence

“…1,2,[4][5][6][7][8] The chemistry of related 4 0 H-spiro[indoline-3,5 0 -isoxazol]-2-ones (1) is much better known, and quite a few methods toward their synthesis have been developed to date. Most of these employ readily available isatin precursors 2 as a synthetic platform (Scheme 1), and typically involve an acid-assisted 1,5-spirocyclization of monooximes of 3-ene-2,5-diones, 9,10 [3 + 2]-cycloaddition of nitrile oxides to 3-methyleneoxindoles, [11][12][13] or metal-catalyzed selective vinylation of isatin oximes with vinylboronic acids. 14 However, any subsequent manipulations at the carbonyl moiety, should they be required, would be limited by the vulnerability of the a-spirocyclic fragment in 1.…”

“…Hz, 1H), 5.67 (s, 1H);13 C { 1 H} NMR (101 MHz, CDCl 3 ) d 177.5, 153.4, 149.7, 135.1, 133.6, 132.1, 131.9, 131.6, 130.7, 129.9, 129.3 (2C), 129.1, 128.6, 128.3 (2C), 126.7, 126.1, 125.8, 125.6, 124.8, 124.7, 122.6, 121.2, 96.8, 57.6; FTIR (ZnSe, lm, cm À1 ): 3070, 2909, 1965, 1746, 1614, 1546, 1451, 1240, 1193, 1059; HRMS (ES TOF) m/z: (M + Na) + calcd for C 26 H 18 N 2 NaO 397.1311; found 397.1306.…”

“…3 Hz, 1H), 7.59-7.49 (m, 3H), 7.41 (d, J ¼ 7.7 Hz, 1H), 7.16 (t, J ¼ 7.7 Hz, 1H), 6.98-6.94 (m, 1H), 6.90 (t, J ¼ 7.3 Hz, 1H), 6.85 (d, J ¼ 7.9 Hz, 1H), 6.59 (d, J ¼ 6.8 Hz, 2H), 5.01 (s, 1H), 2.08 (s, 3H), 2.07 (s, 3H);13 C{ 1 H} NMR (101 MHz, CDCl 3 ) d 177.6, 152.9, 149.9, 136.9, 136.6, 135.8, 131.8, 131.7, 130.3, 130.0, 129.8, 129.2 (2C), 129.1, 128.4 (2C), 126.0, 125.3, 124.8, 121.1, 97.7, 61.5, 19.7, 19.5; FT IR (ZnSe, cm À1 ): 3065, 2929, 2852, 1956, 1904, 1726, 1614, 1537, 1444, 1264; HRMS (ES TOF) m/z: (M + Na) + calcd for C 24 H 20 N 2 NaO 375.1268; found 375.1473. bromonaphthalene (412 mg, 2.00 mmol). Eluent for column chromatography: benzene.…”

A Unique Approach to Catalyst-Free, One-Pot Synthesis of Spirooxindole-Pyrazolines

“…4 Although spirooxindole-pyrazolines are an interesting class of spirooxindoles, they have been less studied than spirooxindole-pyrrolidines. To the best of our knowledge there are only three [5][6][7] procedures for the synthesis of spirooxindole-pyrazolines, and all of them require at least two steps starting from the condensation of isatine and a reactive methylene nucleophile (Scheme 1). Scheme 1 Reported synthesis of spirooxindole-pyrazolines under various conditions requiring at least two steps The importance of spirooxindoles has led to a demand for a synthetic methodology; particularly to access those that are fused to a pyrazole ring.…”