Diazo Glutaconimides: an Unexplored Type of Heterocyclic α‐Diazocarbonyl Compounds Conveniently Evolved into Pyridine‐2,6(1H,3H)‐diones and Oxazolo[5,4‐b]pyridin‐5(4H)‐ones

Abstract

A convenient general approach towards 1,4-disubstituted αdiazo glutaconimides starting from β-substituted glutaconic acid anhydrides has been developed. It involves condensation with amines and subsequent diazo transfer reaction. This new class of diazocarbonyl heterocycles has been converted into a series of polysubstituted pyridine-2,6(1H,3H)-diones and oxazolo[5,4-b]pyridin-5(4H)-ones via a Rh 2 (esp) 2-catalyzed XH-insertion reaction and [3 + 2] cycloaddition with nitriles, respectively. Results and discussion Glutaconimides 5, precursors of the target diazo compounds 4, were obtained by analogy with the methods described in the literature [21] from synthetically available β-substituted glutaconic acid anhydrides 6. [18-19] Initial attempt at the Regitz diazo transfer using an equivalent amount of a base (DBU, TEA, DIPEA) resulted only in a negligible yield of 4. This was

Oxonium Ylides Generated from 1,4‐Disubstituted α‐Diazo Glutaconimides: a Rich Source of Diverse Oxygen Heterocyclic Frameworks

“…Twelve α-diazo glutaconimides 6 a-l employed in this study were prepared in two steps from 3-aryl-substituted [14] as well as 3-methyl-substituted glutaconic anhydrides 7 as described previously. [13] Condensation with aliphatic or, under more forcing conditions, aromatic amines furnished glutaconimides 8 a-l which were subjected to diazo transfer conditions using DIPEA as a base and 4-nitrobenzenesulfonyl azide (4-NsN 3 ) as the diazo group donor. The isolated yields were moderate to good in both steps (Scheme 2).…”

“…), 1.68 (h, J = 7.5 Hz, 1H), 0.96 (t, J = 7.4 Hz, 3H). 13 C { 1 H} NMR (101 MHz, CDCl 3 ): δ 163. 1, 163.1, 161.5, 142.6, 129.4, 128.9, 128.4, 125.2, 124.9, 114.8, 114.0, 110.6, 72.7, 55.5, 41.9, 21.2, 11.4 General procedure for the reaction of α-diazo glutaconimides 6 with THF (preparation of compounds 9 and 10)…”

“…1 H NMR (400 MHz, CDCl 3 ): δ 7.50-7.36 (m, 6H), 6.01 (s, 1H), 4.36 (dd, J = 14.2, 7.5 Hz, 1H), 3.82 (dd, J = 13.0, 5.2 Hz, 1H), 3.70 (ddd, J = 13.5, 11.2, 6.3 Hz, 2H), 3.51 (dd, J = 13.0, 7.5 Hz, 1H), 3.24 (dd, J = 12.9, 8.2 Hz, 1H), 2.69 (tt, J = 7.4, 4.0 Hz, 1H), 2.42 (ddd,J = 16.1,8.4,1.3 Hz,1H),2.27 (dd,J = 15.8,7.7 Hz, 1H), 1.22-1.05 (m, 2H), 0.84-0.74 (m, 1H), 0.64-0.52 (m, 1H). 13 C{ 1 H} NMR (101 MHz, CDCl 3 ): δ 175. 8, 164.4, 158.3, 136.1, 129.3, 129.0, 128.3, 120.7, 79.0, 72.4, 70.6, 65.6, 42.8, 23.9, 8.6, 7.4 dodec-1( 12 3, 166.3, 139.1, 136.9, 134.9, 129.9, 129.0, 127.9, 74.5, 70.7, 67.9, 47.9, 36.6, 23.9, 8.6, 7.4 Yield: 52 mg (84 %).…”

“…1 H NMR (400 MHz, CDCl 3 ): δ 5.84 (q, J = 1.5 Hz, 1H), 4.87 (hept, J = 6.9 Hz, 1H), 4.42 (dd, J = 14.0, 7.0 Hz, 1H), 4.07-3.88 (m, 3H), 3.86-3.72 (m, 2H), 2.30 (qdd, J = 16.1, 7.4, 1.7 Hz, 2H), 2.10 (d, J = 1.5 Hz, 3H), 1.42-1.31 (m, 6H). 13 C { 1 H} NMR (101 MHz, CDCl 3 ): δ 175. 4, 163.7, 157.9, 119.1, 79.4, 73.0, 70.8, 66.0, 45.0, 43.2, 20.2, 18.8, 18.4 dodec-1( 12)-ene-9,11-dione (12 k) 8, 141.3, 137.5, 75.1, 72.0, 68.6, 50.0, 44.9, 35.5, 20.0, 19.1, 17.5…”

“…Yellow powder; mp 152-154°C 1. H NMR (400 MHz, CDCl 3 ): δ 7.53-7.41 (m, 2H), 7.25 (d, J = 8.6 Hz, 2H), 7.20-7.16 (m, 2H), 7.09-6.99 (m, 2H), 6.00 (s, 1H), 3.87 (s, 3H) 13. C{ 1 H} NMR (101 MHz, CDCl 3 ): δ 164.1 (d, C-F, 1 J C-F = 252.9 Hz), 163.2, 163.0, 159.7, 142.5, 129.0 (d, C-F, 3 J C-F = 8.7 Hz), 129.0, 126.8, 116.9 (d, C-F, C-F = 22.0 Hz), 114.8, 111.9, 55.5.…”