Aldehydes and ketones from thioacetals

Studies on the Synthesis of Apoptolidin: Progress on the Stereocontrolled Assembly of the Pseudo Aglycone of Apoptolidin

“…The solvent was removed in vacuo and the residue was diluted with EtOAc (50 mL), washed with saturated NaHCO 3 (10 mL) and brine (10 mL), dried 33 (s, 3 H), 0.33 (s, 3 H), 0.24 (s, 3 H), 0.17 (s, 3 H). 13 …”

“…[13] Condensation of 11 with the titanium enolate derived from the acyloxazolidinethione 12 afforded the aldol adduct 13 in excellent yield (85-90 %) and stereoselectivity (Ͼ95 % de).…”

Synthesis of ( – )-Biopterin Using (S)-Ethyl Lactate as a Starting Material

“…The residue was extracted with ether, and the extract was filtered and concentrated in vacuo. (16). To an ice-cooled solution of 15 (0.20 g, 0.93 mmol) in CH30H (3.5 ml) containing one drop of 2-mercaptoethanol was added I N KOH solution (0.5 ml) under an Ar atmosphere.…”

“…Elution with a mixed solvent of iso-PrOH and ammonia water (4: I) gave a pale yellow solid. This was washed with acetone, CH30H, water and acetone, and dried at 60°C for 4 hr to yield 16 …”

“…After chromatographic separation, 15 was obtained in a pure form in a 60% yield. The construction of the pterin skeleton was achieved by treating A, which had been generated in situ by the hydrolysis of 15, with 2 to afford isopropylidenebiopterin (16) (2S)-Ethyl 2-tetrahydropyranyloxypropionate (3b). To a solution of (S)-ethyllactate 3a (101.0 g, 0.881 mol) in dry CH2CI2 (300 ml) was added 2,3-dihydropyrane (82.0 g, 0.976 mol) and PPTS (1.00 g, 4 mmol) at room temperature.…”