Synthesis of Diaryloxazoles^1-3

Base catalysed rearrangements involving ylide intermediates. Part 18. Competing [1,2], [1,3], and [1,4] rearrangements of ammonium ylides

“…The ether layer was washed with water, dried, and concentrated and the residue distilled to give 2-bromo-l-['H5]phenylpropan-1-one (20 g, 89%), b.p. 1 3 4 1 3 8 "C at 12 mmHg; 6, AX3 system, 6, 5.32, SX 1.88 [JAX 7 Hz, COCHABrC(Hx),]; the spectrum showed no detectable signals for aryl H. ( R,S)-N-Methyl-1 -[ZH5~pheny/ethylumine (26).-A mixture of [2H5]acetophenone (1 1.5 g),' formic acid (90%, 11.76 g), and methylformamide (16.28 g) was heated in an autoclave for 16 h at 190 "C. The product was distributed between ether and aqueous HCI (lo%), the aqueous layer was washed with ether, concentrated to a small volume, made basic (Na,C03), and extracted with ether. The extract was dried and evaporated and the residual oil distilled to give the ['HS]amine ( 26 methyl-1-phenylethylamine (24; R = Me) (13.50 g) at room temperature.…”

TBAI-catalyzed oxidative coupling of β-ketoesters with carboxylic acid: synthesis of α-carboxylic-β-ketoesters

“…β-ketoesters derivatives, which bear substituted groups such as methyl, methoxyl, chloro and bromo at para or ortho positions, all reacted smoothly with 2a to afford the desired corresponding products. Naphthyl substituted β-ketoesters and ethyl acetoacetate also reacted smoothly, albeit in lower yield (entries [7][8]. Generally, β-ketoesters derivatives bearing electron-withdrawing groups were reacted faster than those bearing electron-donating groups.…”

“…1-Ethoxy-1,3-dioxo-3-phenylpropan-2-yl benzoate (3a). 7 9, 165.0, 165.0, 133.9, 133.1, 132.2, 130.8, 130.1, 129.7, 128.6, 128.4, 75.1, 62.7, 14. 8, 165.2, 165.1, 139.7, 133.8, 132.4, 132.1, 130.1, 129.3, 128.6, 128.5, 125.7, 76.3, 62.4, 21.0, 13.9 192.6, 165.3, 165.1, 133.9, 133.9, 133.8, 132.6, 130.6, 130.2, 129.1, 128.6, 128.5, 128.5, 126.8, 125.5, 124.2, 76.7, 62.4, 13.8 9, 165.3, 165.1, 144.7, 134.4, 134.2, 130.2, 129.3, 129.2, 128.8, 125.8, 74.9, 62.4, 21.7, 13.9 165.5, 164.8, 164.1, 134.4, 134.2, 132.3, 129.3, 128.8, 120.8, 113.9, 74.8, 62.4, 55.5, 13.9 5, 165.0, 164.3, 140.4, 134.3, 134.3, 131.5, 129.3, 128.9, 128.8, 127.0, 75.0, 62.6, 13.9 3H),7.60 (t,J 7.4 Hz,1H),7.48 (t,J 7.8 Hz,2H),7.40 (t,J 7.5 Hz,1H),2H),6.56 (s,1H),2H), 2.60 (s, 3H), 1.22 (t, J 7.1 Hz, 3H), 13 C NMR (125 MHz, CDCl 3 ) δ 189. 9, 165.8, 165.4, 141.1, 134.4, 134.2, 132.9, 131.8, 131.3, 129.2, 128.8, 127.8, 125.9, 74.8, 62.4, 21.7, 13.9 4, 165.0, 163.7, 134.5, 134.3, 134.2, 133.5, 132.2, 131.2, 129.3, 128.8, 128.1, 126.8, 75.0, 13.9 4, 165.0, 164.2, 134.6, 134.3, 133.5, 132.2, 129.3, 128.8, 127.4, 122.4, 75.0, 62.6, 13.9 7, 171.5, 165.2, 140.0, 134.3, 134.2, 129.2, 128.8, 128.5, 128.3, 126.4, 74.5, 62.5, 35.3, 30.6, 13.9 …”

Oxazoles in carboxylate protection and activation

“…Earlier work demonstrated that the formation of small and large ring lactones takes place readily through intramolecular acylation of triamide by w-substituted hydroxy groups.7,40 More recently it has been shown that the cyclization of a hydroxy triamide is a promising method of forming medium-ring lactones as exemplified by the synthesis of the 10-membered plant product, phoracantholide I (31). 47 The procedure for its formation follows the lines developed earlier and is outlined in Scheme VIII.…”