Highly Selective Electrophile‐Induced Cascade Reactions between o‐Alkynylbenzaldehydes and Styrene Oxides Leading to the Formation of 1‐Naphthyl Ketones

Abstract

An efficient method for the synthesis of naphthalene derivatives through reaction of o-alkynylbenzaldehydes and styrene oxides in the presence of molecular iodine was developed. The reaction involves Meinwald rearrangement of styrene oxides to form the corresponding aryl acetaldehydes. The enol forms of aryl acetaldehydes might undergo [4+2] benzannulation reactions with iodinated benzopyrilium ions,

Vinylogous Nicholas reactions in the synthesis of bi- and tricyclic cycloheptynedicobalt complexes

“…The combined yield was 80%, and a ratio of cyclized:elimination of 1: 8, 152.8, 151.6, 142.9, 141.0, 138.4, 132.8, 131.5, 128.5, 126.9, Compound 15b (0.5127 g, 1.685 mmol) was complexed using General Procedure G to afford complexed product 3b (0.9250 g, 1.568 mmol, 93%) as a dark green solid, which eluted off a flash chromatographic column of neutralized silica using 10: 0, 169.8, 144.3, 139.3, 138.5, 115.9, 101.6, 94.4, 65.5, 37.5, 32.6, 32.1, 27.0, 26.9, 25.9, 20.1, -1.1;IR (KBr): 2926, 2854, 2020, 1229 3, 147.6, 147.0, 133.9, 118.4, 95.4, 90.0, 39.2, 38.4, 34.7, 33.8, 32.2, 26.5, 26.1;IR (KBr): 2924, 2851, 2016, 1598, 1432, 1213 afforded the product 18a as a yellow oil (0.8583 g, 3.646 mmol, 84%), which was characterized as spectroscopically identical to reported values. 12…”

Asymmetric reactions involving isobenzopyrylium ion intermediates

“…[4][5][6][7][8] Then other transition metal catalysts (CuX2, 9-10 W, [11][12][13][14] PdX2, [15][16][17] PtX2, [18][19][20][21][22] Rh(I) 23 , InX3 [24][25][26] etc.) and electrophilic activators (I2, [27][28][29] IPy2BF4, [30][31][32] TfOH, [33][34][35] etc.) proved to be effective in the intramolecular cycloisomerization of o-alkynylaryl carbonyl compounds (Scheme 1C).…”

Why Does Gold(III) Porphyrin Act as a Selective Catalyst in the Cycloisomerization of Allenones?

“…Homogeneous catalysis by gold complexes is becoming increasingly popular for the formation of C-C, C-N, C-S, and C-O bonds in organic transformations. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Gold catalysts are being actively and very efficiently utilized for the cyclization of alkynes and allenes. [17][18][19][20][21][22] Lewis acid catalysts like AuCl 3 or AuPPh 3 Cl are now routinely utilized for such transformations.…”

“…Homogeneous catalysis by gold complexes is becoming increasingly popular for the formation of C−C, C−N, C−S, and C−O bonds in organic transformations. − Gold catalysts are being actively and very efficiently utilized for the cyclization of alkynes and allenes. − Lewis acid catalysts like AuCl 3 or AuPPh 3 Cl are now routinely utilized for such transformations. − However, the major goal in the area of catalysis by Au-salts is to develop very efficient as well as chemoselective reagents with high catalytic turnovers. In this context, metalloporphyrin-mediated functionalization of hydrocarbons has been very effective for organic and biomimetic studies. − The presence of the porphyrin ring provides an innovative means to fine-tune the steric and electronic requirements of the reactions and thus leads to very selective product formation.…”