38. Synthetic long-chain aliphatic compounds. Part I. Introduction. Myristic, stearic, and tricosanoic acids

Synthesis of 7‐Triazole‐substituted Camptothecin via Click Chemistry and Evaluation of in vitro Antitumor Activity

“…Typically, according to the methods described previously, [26,27] azido amino acids 10a-10d were obtained as a colorless oil from the corresponding bromide 7a-7d respectively in three steps, which was further transformed into hydroxamates 9a-9d according to the reported method. Typically, according to the methods described previously, [26,27] azido amino acids 10a-10d were obtained as a colorless oil from the corresponding bromide 7a-7d respectively in three steps, which was further transformed into hydroxamates 9a-9d according to the reported method.…”

The synthesis of (±)-10a-homo-11a-carbathromboxane A1, a stable thromboxane A analogue

“…The residual oil (1.1 g) was purified by 1.p. (16).-A solution of borane-THF complex (0.83~; 2.0 ml, 1.7 mmol) in THF was slowly added dropwise to a stirred solution of the alkene (15) (0.40 g, 1.2 mmol) in dry THF (5 ml) maintained at 0 "C under argon.…”

“…The resultant solution was stirred at room temperature for 2.5 h and then cautiously treated successively with water (0.2 ml), aqueous sodium hydroxide ( 3 ~; 0.6 ml), and aqueous hydrogen peroxide (30%; 0.6 ml) (reaction temperature 30-35 "C) and heated at 45-50 "C for 1 h. The cooled mixture was diluted with ether (8 ml) and water (3 ml), the organic layer was separated, and the aqueous layer was extracted with ether (2 x 3 ml). The combined organic layers were washed successively with water and saturated aqueous sodium chloride, dried (K2C03, MgS04), and concentrated to afford the hydroxy-THP ether (16) (0.42 g, 99%), sufficiently pure to proceed with the next stage. An analytical sample was purified by p. (17) and (18).-A solution of the alcohol (16) (0.20 g, 0.59 mmol) in dry dichloromethane (0.8 ml) was added in one portion to a vigorously stirred suspension of pyridinium chlorochromate (0.26 g, 1.2 mmol) in dry dichloromethane (2 ml) containing anhydrous sodium acetate (22 mg, 0.27 mmol), and the resultant mixture was stirred under argon at room temperature for 1.8 h. Dry ether (10 ml) was then added, the supernatant liquid was decanted, and the insoluble residue was washed thoroughly with dry ether (3 x 5 ml) to leave a granular solid.…”

“…Use of di-iodomethane and magnesium amalgam,g a possible one-step reaction for the transformation (6) -(15), failed with (6), again probably for steric reasons since the expected product (12a) was readily formed from the unsubstituted ketone (2). Hydration of the alkene THP ether (15) by treatment with borane-THF complex followed by alkaline hydrogen peroxide gave the hydroxy THP ether (16). It was anticipated that the ~i ~~( e x o -2 , exo-3)-isomer of (16) would predominate since hydroboration normally proceeds by an anti-Markovnikov cisaddition from the less hindered side of the molecule, and the endo-face of (15) was considered to have least steric hindrance; the em-alkyl group adjacent to the carbonyl group was expected to render greater steric hindrance to the exo-face than the ethano bridge to the endo-face.…”

“…It was anticipated that the ~i ~~( e x o -2 , exo-3)-isomer of (16) would predominate since hydroboration normally proceeds by an anti-Markovnikov cisaddition from the less hindered side of the molecule, and the endo-face of (15) was considered to have least steric hindrance; the em-alkyl group adjacent to the carbonyl group was expected to render greater steric hindrance to the exo-face than the ethano bridge to the endo-face. Upon oxidation with pyridinium chlorochromate in sodium acetate-buffered dichloromethane the hydroxy THP ether (16), which appeared homogeneous by t.l.c., gave an 8 : 3 mixture (distinguished and estimated by 'H n.m.r. spectroscopy) of the aldehydes (17) and (18).…”