trans-6-Aminocyclohept-3-enols, a New Designed Polyfunctionalized Chiral Building Block for the Asymmetric Synthesis of 2-Substituted-4-hydroxypiperidines

Abstract

trans-6-Aminocyclohept-3-enols 18 and ent-18 are new designed polyfunctionalized chiral building blocks for piperidine alkaloids synthesis and are prepared in high yields from the enzymatically derived cyclohept-3-ene-1,6-diol monoacetate (-)-8. Efficient highly enantioselective syntheses of cis-4-hydroxypipecolic acid (1) and piperidines 3 and 4, in both enantiomeric forms, are described. [reaction: see text]

Identification and biosynthesis of tropone derivatives and sulfur volatiles produced by bacteria of the marine Roseobacter clade

“…The tautomer 5-cycloheptene-1,3-dione (42b) was synthesized from cyclohept-5-ene-1,3-diol (41), readily available via a three step synthesis from tropone according to Celestini et al (Scheme 2). 26 Oxidation of the diol with Cr(VI) oxide gave 5-cycloheptene-1,3-dione (42b), eluting at the same retention time and showing the same mass spectrum as compound A. Attempts to isomerize this compound to 4-cycloheptene-1,3-dione (42a) or to purify it by column chromatography failed because of its instability.…”

“…Although L-phenylalanine is a precursor for phenylacetate by transamination and oxidative decarboxylation, a similar pattern of aromatic volatiles did not occur during growth on L-phenylalanine and L-histidine, possibly because this experiment was based on a minimal medium and not a full medium. The principal compound produced by P. gallaeciensis from phenylacetate, ethyl benzoate (26), is a typical plant volatile, but has never been reported from bacteria. The higher homolog ethyl phenylacetate (33) was also identified from bacteria for the first time, but the related butyl phenylacetate is produced by Streptomyces.…”

“…The diol 41 was prepared according to the method of Celestini et al 26 This diol (0.1 g, 0.78 mmol) was dissolved in a mixture of diethyl ether (15 mL) and dichloromethane (5 mL), and Celite (0.31 g) was added. The mixture was cooled to 0 • C, and CrO 3 (0.31 g, 3.1 mmol) was added in small portions.…”

The role of biocatalysis in the asymmetric synthesis of alkaloids

“…33 Lesma and co-workers, on the other hand, have extended the concept of hydrolytic desymmetrisation of meso-diacetates to the cycloheptene derivative 11, obtaining the monoacetate (1S,6R)-12 (Scheme 3) in 95% yield and .97% ee using lipase PS. 34,35 From this building block, several 4-hydroxypiperidine derivatives such as cis-4-hydroxy-2-pipecolic acid, a hydroxylated quinolizidine 13, and the piperidine alkaloid (2)halosaline (14, Scheme 3) were prepared, 34,36 the latter in a very elegant sequence involving ruthenium-catalysed ringrearrangement metathesis as a key step.…”

Water‐Mediated Synthesis of Anthelmintic Piperidinols and Their Molecular Docking Studies

“…In addition, they act as sodium and calcium channel blockers, estrogen receptor modulators, liver glycogen phosphorylase inhibitors, map kinase inhibitors and dopamine D2 receptor antagonist . The traditional routes for synthesis of piperidinols involve gold mediated chemoselective reduction of amide followed by Ferrier rearrangement, silica chloride catalyzed and ultrasound assisted reduction of 4‐piperidinone, NaBH(OAc) 2 assisted reaction of aldehydes with amines, enzymatic transformation of trans‐6‐aminocyclohept‐3‐enols, phosphomolybdic acid mediated aza‐Prins‐cyclization and solid phase synthesis from 1,2,3,6‐tetrahydro‐pyridines . Most of these methods suffer from drawbacks such as tedious workup procedure, harsh reaction conditions, prolonged reaction time, unsatisfactory yields and use of strongly basic conditions.…”