Improved Procedure for the Reduction of N-Acyloxazolidinones

A Practical Approach to Synthesize the C(9) –C(24) Fragment of (+)‐Discodermolide

“…The crude product was purified by flash chromatography (ethyl acetate/petroleum ether＝1/2, V/V) to af- (d, J＝6.9 Hz, 3H), 0.78 (d, J＝6.9 Hz, 3H). 13 C NMR (100.7 MHz, CDCl 3 ) δ: 159. 1, 130.5, 129.2, 113.7, 98.6, 80.5, 72.7, 72.1, 64.9, 56.1, 55.2, 36.6, 14.6, 9.5.…”

“…1 H NMR (CDCl 3 , 300 MHz) δ: 7.31-7.18 (m, 7H), 6.83 (d, J＝8.4 Hz, 2H), 4.61-4.54 (m, 2H), 4.49-4.42 (m, 1H), 4.38-4.36 (m, 2H), 4.17-3.98 (m, 2H), 3.95-3.89 (m, 1H), 3.82-3.78 (m, 1H) (d, J＝6.9 Hz, 3H). 13 C NMR (CDCl 3 , 100.7 MHz) δ: 175. 4, 159.1, 153.1, 135.6, 130.6, 129.4, 129.1, 128.9, 127.3, 113.7, 98.8, 82.7, 72.7, 71.7, 66.1, 56.4, 55.9, 55.2, 41.0, 37.7, 37.3, 14.7, 11.9;IR (KBr) ν: 2972, 2937, 1779, 1702, 1612, 1585, 1513, 1455, 1383, 1032 …”

Structures and Total Syntheses of the Plecomacrolides

“…The alkene 169 is a homolog of 27 (Scheme 3) and was subjected to the steroselective hydroboration [41a,c], alkaline oxidation, and the Evans' aldol reaction [106] with the boron enolate prepared from N-propionyl-(4S)-benzyl-2-oxazolidinone to provide the syn aldol product 170 as the sole isomer in 72% overall yield from 169. The chiral auxiliary in 170 was removed by lithium borohydride reduction [107], the resultant C11-primary alcohol was selectively converted into the tosylate, and the C9-secondary alcohol was protected as the TBS ether. Acetylide alkylation with the above tosylate was then carried out in DMSO to afford, after global deprotection of the silyl ether and the acetal, the alkyne 171 in 46% yield from 170.…”

Asymmetric Biomimetic Oxidations of Phenols: Enantioselective Synthesis of (+)- and (-)-Dehydrodiconiferyl Alcohol

“…After the dimerization step the camphor sultam auxiliaries were removed by reduction with LiAlH 4 /THF 12 and the oxazolidinones were removed by reduction with LiBH 4 /THF. 17 Table 1 gives the results for the oxidations of chiral phenols 6a-d and 9. …”