Homologisierung von aromaten mit diazomethan und kupfersalzen

Synthesis of dicyclopenta[ef,kl]heptalene (azupyrene). II. Routes from 1,6,7,8,9,9a-hexahydro-2H-benzo[c,d]azulen-6-one and 5-phenylpentanoic acid

“…Recrystallization of the second solid from re-hexane gave 0.15 g (33%) of 17, mp 119.5-121.5°, identical (ir and nmr) with the product from A. 5,6,6a,7,8,9,4, 19). Method A.-To a cooled (ice bath), stirred mixture of 7.52 g (35.8 mmol) of crude ketone 16 and 100 ml of absolute ethanol was added 1.01 g (26.4 mmol) of sodium borohydride.…”

“…Scheme III 20 platinic acid were then added, any excess borohydride was destroyed, and the solution was brought to the required acidity with hydrochloric acid, and hydrogenative reduction of the carbon-carbon double bond and cleavage of the benzylic hydroxyl were all effected in one continuous operation to give 7 as the cis isomer (19) in 66% yield. The intermediate alcohol 18 could be isolated and was characterized.…”

“…It was hoped that decarboxylation would occur concomitantly and a trail reaction with l,2,3,6-tetrahydro-6-azuloic acid24 was found to give azulene in 12% yield. Application of the procedure to the tetracyclic acid gave azupyrene (25; 3.8% from 19) as thermally stable, bronze crystals.…”

Carbon-carbon bond formation promoted by transition metal carbonyls. 18. New synthesis of troponoid compounds via the iron carbonyl promoted cyclocoupling between polybromo ketones and 1,3-dienes

“…2.4.7-TrimethyItropone (9), Bromination of 2,4,7-trimethyl-4cycloheptenone (2, 46.4 mg, 0.305 mmol) with PHT (925 mg, 1.86 mmol) was carried out in THF (3 mL) at 25 °C for 12 h and workup gave a yellow oil (105 mg). The product was mixed with LiCl (200 mg, 4.82 mmol) in DMF (2 mL) and heated at 140 °C for 1 h. Purification of the crude product by TLC (1:1 benzene-hexane, two developments, and 1:10 ether-benzene) afforded 9 (20.7 mg, 46%, R/ 0.34): IR (CHCI3) 3007 (m), 2952 (w), 2920 (m), 1684 (w), 1624 (w), 1604 (w), 1559 (s), 1518 (m), 1460 (w), 1425 (w), 1370 (m), 1234 (w), 1160 (m), 1034 (w), 1005 (w), 839 cm"1 (m); NMR (CDC13) 2.29 (br s, 3 CH3), 6.6-6.9 (m, H5), 7.1-7.3 (m, H3 and H6); mass spectrum m/e 148 (M+), 120, 105 (base peak); exact mass spectrum m/e 148.0893 (caled for Ci0H,2O, 148.0888).…”

Catalytic Conversion of Furans and Pyrroles to Natural Products and Analogues Utilizing Donor‐Acceptor Substituted Cyclopropanes as Key Intermediates

“…Another aromaticity breaking reaction that is long known for pyrroles and furans is the [2+1] addition of carbenes to form cyclopropanated adducts . We were especially intrigued by the possibility to access monocyclopropanated adducts 4 or 5 by cyclopropanation with diazoesters (Figure ), which we envisioned would offer unique opportunities as building blocks in stereoselective synthesis: both cyclopropane bonds connected to the ester carbon are in a donor‐acceptor relationship with the oxygen or nitrogen atom of the heterocycle, which should give rise to ring‐opening chemistry, as it is well established for this class of three‐membered ring compounds…”