Oxygenative and Dehydrogenative [3 + 3] Benzannulation Reactions of α,β-Unsaturated Aldehydes and γ-Phosphonyl Crotonates Mediated by Air: Regioselective Synthesis of 4-Hydroxybiaryl-2-carboxylates

Abstract

Regioselective synthesis of 4-hydroxybiphenyl-2-carboxylates via the base-mediated oxygenative [3 + 3] benzannulation reaction of α,β-unsaturated aldehydes and γ-phosphonyl crotonates is reported. A hydroxyl group is installed in the final product on the originally phosphorus-bound carbon via a novel oxygenative and dehydrogenative transformation. The reaction proceeds rapidly in an open flask, uses atmospheric oxygen as an oxidant, and affords good yields of substituted biaryl phenols.

Benzannulation Reactions: A Case for Perspective Change From Arene Decoration to Arene Construction

“…The aerobic oxidative reaction proceeds rapidly in open flask under mild conditions (Scheme 15). [24] It is proposed that the phosphorous bearing carbon is transformed to the phenolic oxygen bearing arene carbon via aerial oxidation of a cyclic intermediate as depicted in the mechanism (Scheme 15).…”

Base-Mediated Cyclopentannulation of Ynones with Amino Crotonates for Regio- and Stereoselective Synthesis of Pentafulvenes and Cyclopenta[c]quinolines

“…3la (115 mg) was obtained from 1k (106 mg, 0.5 mmol) and 2a following general procedure B. Yield 60%; dark yellow solid; mp 163−166 °C; R f = 0.57 (SiO 2 , 1% EtOAc/Hexanes); 1 H NMR (500 MHz, CDCl 3 ) δ 13.21 (d,J = 13.2 Hz,1H),7.91 (d,J = 13.2 Hz,1H),4H),4H), 7.21 (dd, J = 5.0, 3.0 Hz, 1H), 7.17 (dd, J = 5.0, 1.2 Hz, 1H), 7.08 (dd, J = 8.0, 4.2 Hz, 3H), 6.43 (s, 1H), 3.68 (s, 3H); 13 C{H} (125 MHz, CDCl 3 ) δ 169. 2, 145.8, 144.0, 142.8, 139.7, 139.5, 139.3, 136.6, 129.9, 129.8, 128.5, 127.2, 124.8, 124.3, 123.4, 122.8, 117.3, 116.8, 111.1, 51.2;IR (KBr) ν 3276, 2928, 1641, 1596, 1279 2, 153.0, 145.6, 143.1, 139.9, 137.4, 136.8, 129.9, 129.7, 128.4, 126.9, 124.4, 123.9, 123.6, 117.1, 116.3, 111.2, 51.5, 30.1, 25.6, 23.3, 22.4;IR (neat) ν 3265, 2932IR (neat) ν 3265, , 1643IR (neat) ν 3265, , 1596IR (neat) ν 3265, , 1218 384.1964; found, 384.1951.…”

“…3na (123 mg) was obtained from 1m (110 mg, 0.5 mmol) and 2a following general procedure B. Yield 63%; pale yellow solid; mp 132−136 °C; R f = 0.59 (SiO 2 , 1% EtOAc/Hexanes); 1 H NMR (500 MHz, CDCl 3 ) δ 13.12 (d, J = 13.2 Hz, 1H), 7.62 (d,J = 13.3 Hz,1H),2H),8H), 7.25 (d, J = 1.6 Hz, 1H), 7.13−7.05 (m, 3H), 6.34 (s, 1H), 3.65 (s, 3H), 2.31 (s, 3H); 13 C{H} (125 MHz, CDCl 3 ) δ 13 C NMR (126 MHz, CDCl 3 ) δ 169. 3, 148.9, 145.0, 143.3, 139.7, 139.3, 137.3, 136.1, 131.3, 130.2, 129.7, 129.2, 127.4, 127.3, 126.6, 125.2, 125.0, 124.6, 118.2, 117.2, 110.4, 51.1, 20.8;IR (KBr) ν 3247, 2930, 1642, 1597, 1277 Methyl (Z)-4-(4-Methoxyphenyl)-2-phenyl-5-((phenylamino)methylene) Cyclopenta-1,3-diene-1-carboxylate (3oa).…”

“…3pa (150 mg) was obtained from 1o (163 mg, 0.5 mmol) and 2a following general procedure B. Yield 60%; browinsh yellow solid; mp 173−176 °C; R f = 0.53 (SiO 2 , 6% EtOAc/Hexanes); 1 H NMR (500 MHz, CDCl 3 ) δ 13.18 (d, J = 13.4 Hz, 1H), 7.66 (d,J = 13.3 Hz,1H),2H), 7.36 (t, J = 7.7 Hz, 4H), 7.29 (t, J = 7.3 Hz, 1H), 7.15 (dd, J = 7.7, 4.2 Hz, 4H), 6.86 (s, 1H), 6.34 (s, 1H), 6.05 (dd, J = 9.8, 7.3 Hz, 2H), 3.64 (s, 3H); 13 C{H} (125 MHz, CDCl 3 ) δ 169.2, 148. 4, 147.0, 143.9, 143.6, 139.6, 139.2, 130.7, 129.8, 129.2, 127.3, 127.2, 126.6, 125.5, 124.9, 117.5, 117.0, 115.0, 112.9, 112.2, 110.8, 101.9, 51.1;IR (KBr) ν 3284, 2932, 1598, 1497, 1278, 771 cm −1 ; HRMS (ORBITRAP) m/z [M + H] + calcd for C 27 H 21 BrNO 4 502.0654; found, 502.0648.…”

Recent Progress in Transition‐Metal‐Free, Base‐Mediated Benzannulation Reactions for the Synthesis of a Diverse Range of Aromatic and Heteroaromatic Compounds

“…Recently, a t BuOK‐mediated oxygenative [3+3] benzannulation reaction of α,β‐unsaturated aldehydes 96 with γ‐phosphonyl crotonates 97 for the regioselective construction of 4‐hydroxybiphenyl‐2‐carboxylates 98 was reported by Menon and co‐workers (Scheme ) . They used two equivalents of base in MeCN at room temperature to afford various 4‐hydroxybiphenyl‐2‐carboxylate derivatives in good yields.…”