191470-44-7

Upstream product

• 56613-80-0 D-2-phenylglycinol 
• 156873-51-7 (6S)-1-[(1R)-2-hydroxy-1-phenylethyl]-6-methyl-2-piperidone 
• 205526-51-8 (R)-2-[((R)-4-[1,3]Dioxolan-2-yl-1-methyl-butyl)-(2,4,6-trimethoxy-benzyl)-amino]-2-phenyl-ethanol 
• 205526-50-7 (2R,4R)-N-(2,4,6-trimethoxybenzyl)-2-methyl-4-phenyl-1,3-oxazolidine 
• 204845-22-7 (R)-N-2,4,6-trimethoxybenzylphenylglycinol 
• 75-16-1 methylmagnesium bromide 
• 204845-25-0 (3R,5R)-5-methyl-3-phenyl-2,3,6,7,8,8a-hexahydro-5H-oxazolo[3,2-a]pyridine 

Relevant academic research and scientific papers

Stereocontrolled preparation of cis- and trans-2,6-dialkylpiperidines via diastereoselective reaction of 1-aza-4-oxabicyclo[4.3.0]nonane derivatives with Grignard reagents

We report here the syntheses of cis- and trans-2,6-disubstituted piperidines using chiral 1-aza-4-oxabicyclo[4.3.0]nonane synthon 1, which shows high reactivity toward nucleophilic attack at its C-5 position. Bicyclic compounds resembling synthon 1 were transformed to cis- and trans- 2,6-disubstituted piperidine derivatives via reactions with various Grignard reagents in a stereospecific manner. Using this methodology, (+)-solenopsin A (2b) and both enantiomers of isosolenopsin A (3a and 3b) were synthesized in an enantioselective manner from a single enantiomeric source.

Asymmetric synthesis of (+) and (-) trans-2,6-dimethylpiperidines

(+) aid (-) trans-2,6-dimethylpiperidines 9 have been prepared from diastereomeric lactams 6 and 11, both available from (R)-(-)-phenylglycinol 4. Diastereoselective C-2 alkylation afforded oxazolidines 7 and 12. Reduction of 7 with LiAlH4 or NaBH4 led to trans-2,6-8 with total retention of configuration. When 12 was reduced with NaBH4, trans derivative 13a was isolated as the major isomer. A mechanism is proposed to explain the different results.

Facile diastereoselective reactions of chiral 1,3-oxazolidines with grignard reagents; asymmetric syntheses of 2-substituted and 2,6-disubstituted piperidines

(S)- and (R)-2-Phenylpiperidines, (S)- and (R)-2-methylpiperidines, meso- and (2R, 6R)-2,6-diphenylpiperidines, and meso- and (25, 65)-2,6-dimethylpiperidines were synthesized asymmetrically starting from the diastereoselective addition of Grignard reagents to chiral 1,3-oxazolidines, converting of 1-aza-4-oxabicyclo[4.3.0]nonane derivatives as pivotal intermediates.