Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ^{5, 7, 9}‐des‐A‐östratrien

Abstract

Mitteilung [l]Summavy. A 18-step transformation of dehydroabietic acid (I) into ketone 40, convenient starting material for the preparation of 14a-methylsteroids, is described.Seit iiber 20 Jahren berichteten verschiedene Arbeitsgruppen iiber Versuche zur Umwandlung von Dehydroabietinsaure (1) [Z]

Total synthesis of halogenated monoterpene marine natural products via the Diels-Alder reaction

“…Qualitatively, a similar rate difference was observed for the reaction of 5 or 6 with butadiene (7) or with isoprene (8); i.e., 5 undergoes cycloaddition faster than 6. A quantitative assessment of the rate difference in the isoprene reactions is difficult because of the additional complication of regioisomeric products.…”

“…To this was added 6 g (0.056 mol) of a 50:50 mixture of cis-and imns-3-chloro-2-methylpropenol.8® The mixture was stirred for 6 h and then filtered through a Celite pad. After evaporation in vacuo the filtrate gave an average of 3.5-4.0 g (0.033-0.038 mol) in a yield of 59-68% as a 50:50 mixture of cts-3-chloro-2-methylpropenal (5) and the corresponding trans isomer 6. The aldehyde mixture was immediately sealed under vacuum in a thick walled glass tube in the presence of 11.0 g (0.2 mol) of butadiene, 0.88 g (0.004 mol) of BHT,35 and 0.23 g (0.004 mol) of propylene oxide made up to 40-mL total volume with dry toluene.…”

“…1.21 (s, 3 ), 1.50 and 1.59 (ABq, 2 H, J = 9.5 Hz and other fine coupling), 3.16 (bs, 2 ), 5.02 (d, 1 H, J = 3.6 Hz), 6.25- Reduction of Isoprene Adducts 12/13 and 14/15 with Lithium Aluminum Hydride. To a solution of 0.2 g (1.16 mmol) of the aldehyde mixture 12/13 or 14/15 dissolved in 3 mL of dry ether was added 0.044 g (1.16 mmol) of lithium aluminum hydride.…”

“…36a: NMR (CDC13 250 MHz) 1.28 (s, 3 ), 1.94-2.15 (m, 2 H), 2.27-2.34 (m, 2 H), 3.85 (dd, 1 H, J = 11.9, 3.6 Hz), 3.87 and 3.93 (AB q, 2 H, J = 10.3 Hz), 5.54 (bs, 1 H), 5.87 and 6.05 (AB q, 2 H, J = 13. 5 NMR (CDC13 250 MHz) 1.22 (s, 3 ), 2.10-2.67 (m, 4 H), 3.93 (bs, 2 H), 3.92 (dd, 1 H, J = 5.4, 8.4 Hz), 5.77 (bs, 1 ), 6.06 and 6.12 (AB q, 2 H, J = 13.6 Hz); 13C NMR (CDC13) 25.6, 33.9, 37. (±)-[liZ-[la(S),2a]]-l-(2-Chloroethenyl)-2,4-dichloro-lmethyl-5-methylenecyclohexane (2).6 To a solution of the allylic bromide 36, 33.8 mg (0.12 mmol), in 1.5 mL of CHC13 under a reflux condenser and drying tube was added 29.0 mg (0.13 mmol) of phenyldichloroiodine.23 The solution was refluxed for a period of 1 hour, and TLC indicated the formation of 3 or 4 different products along with complete reaction of the starting material.…”

Synthetic Study toward Total Synthesis of (±)-Germine: Synthesis of (±)-4-Methylenegermine

“…We hoped to do this by applying Kabalka’s method: the reduction of the tosylhydrazone from 3 with catecholborane. This took place to give the tricyclic olefin 4 in 73% yield. Not only was the cis stereochemistry of the A/B system produced, but the double bond was also placed correctly for the oxygenation of ring A. Oxidation of 4 with peracetic acid in DCM, at −10 °C, gave a 4:1 mixture of the epoxides 5α and 5β .…”