An approach to tricyclo[8.4.0.04.7] Tetradecahepta-1,3,5,7,9,11,13,ENE (benzo[1,2-α]cyclobuta [1,2-ecyclooctatetraene)

Practical Synthesis of (Z)‐Polyaromatic and Heteroaromatic Vinylacetylenes.

“…The residue was purified by flash column chromatography on silica gel using 9:1 petroleum ether/ ethyl acetate as eluent to give 5.58 g (75%) of the product as white solid. Spectroscopic data obtained for 3i were consistent with that reported in the literature7 . 1 H NMR (300 MHz, CDCl 3 ) _ 0.25 (9H, s), 5.51 (1H, d, J = 12.0 Hz), 6.52 (1H, d, J = 12.0 Hz), 7.21 (2H, m), 7.55 (3H, m), 7.78 (1H, d, J = 8.4 Hz),…”

“…The product contains Z and E isomers in 13:1 Z/E ratio. 1 H NMR (Z isomer 5 ) (300 MHz, CDCl 3 ) _ 6.79 (1H, d, J = 8.1 Hz), 7.45 (1H, d, J = 8.1 Hz), 7.55 (1H, td, J = 6.9, 1.2 Hz), 7.72 (1H, td, J = 6.9, 1. (Z)-2-(_-bromovinyl) napthalene 2i: Compound 2i was synthesized analogously to 2e from bromomethyltriphenylphosphonim bromide (19.55 g, 44.82 mmol), potassium tertbutoxide (5.03 g, 44.82 mmol) and 2-napthalene carboxaldehyde (5.00 g, 32.01 mmol) in 150 mL of dried THF.…”

“…were consistent with the literature data. 7 (mp = 84-87 °C); 1 (Z) 2-But-1-en-3-ynyl-9H-fluorene 4j: Compound 4j was synthesized analogously to compound 4a from silyl capped enyne 3j (0.80 g, 2.0 mmol), K 2 CO 3 (0.76 g, 5.0 mmol) in 30 mL of MeOH. The crude was purified by flash column chromatography on silica gel using hexanes to yield the product as a white solid (0.57 g, 97 %).…”

Catalytic Asymmetric Total Synthesis of Exiguolide

“…We have previously reported Cinchona alkaloid-catalyzed cyclo-condensation of an aldehyde and an acid chloride accordingt oN elson's protocol. [14,15] In this particularc ase, aldehyde 7, [16] which is readily availablef rom propargyl alcohol, was reactedw ith propionyl chlorideu sing 12.5 mol %o fT MS-QN and magnesium chloride at À78 8Ct og ive b-lactone 6 in excellent enantioselectivity and diastereoselectivity. [17] The b-lactone 6 was transformed into the Weinreb amide 14 and subsequent MOM protection afforded compound 15 in 83 %y ield.…”