Stereoselective synthesis of new monoterpene β-amino alcohols

The regio- and stereoselective osmium-catalysed aminohydroxylation of (+)-2-carene (99% ee), and (+)-3-carene (99% ee), (?)-β-pinene (99% ee) and (?)-camphene (75% ee) with chloramine-T is described. The products β-hydroxy-p-toluenesulfonamides were reduced with sodium in liquid ammonia to give the corresponding β-amino alcohols with 48–83% yields. The methylation-reduction of β-hydroxy-p-toluenesulfonamides gave β-methylamino alcohols with 33–55% yields.     

One-pot synthesis of α-amino phosphonates from α-amino acids and β-amino alcohols

The one-pot radical fragmentation-phosphorylation reaction of α-amino acids and β-amino alcohols affords α-amino phosphonates in good yields. The reaction was applied to the synthesis of potentially bioactive phosphonates.     

A new facile diastereoconversion of 2-amino alcohols involving a novel cyclocarbamation

A new practical method for diastereoconversion of 2-amino alcohols was performed by treatment of N-Cbz- derivatives with trifluoromethanesulfonic anhydride or thionyl chloride, followed by ring cleavage of the resulting oxazolidin-2-ones     

Preparative synthesis of β-amino alcohols from α-amino dicarboxylic acid derivatives

A low-expensive preparative procedure has been developed for the synthesis of protected β-amino alcohols from α-amino dicarboxylic acid derivatives.     

N-thioacyl 1,3-amino alcohols: synthesis via ring-opening of oxiranes with thioamide dianions and applications as key intermediates leading to stereochemically defined 5,6-dihydro-4H-1,3-oxazines and 1,3-amino alcohols

N-Thioacyl 1,3-amino alcohols were synthesized via the ring-opening of oxiranes with thioamide dianions generated from N-benzyl thioamides and BuLi in a highly regio- and stereoselective manner. The diastereomers of N-thioacyl 1,3-amino alcohols were readily separated by column chromatography to give stereochemically defined N-thioacyl 1,3-amino alcohols. They underwent intramolecular cyclization with Bu4F and EtI to give 5,6-dihydro-4H-1,3-oxazines. The reaction was specific with anti-N-thioacyl 1,3-amino alcohols, and cis-5,6-dihydro-4H-1,3-oxazines were obtained with high efficiency, whereas the reaction of a syn-alcohol gave a thioimidate as a major product. The reduction of N-thioacyl 1,3-amino alcohols with LiAlH4gave N-alkyl 1,3-amino alcohols in high yields. The use of optically active propylene oxide as a starting material gave the corresponding oxazine and alcohols in optically pure forms.     

Solid-state hosts by the template polymerization of columnar liquid crystals: locked supramolecular architectures around chiral 2-amino alcohols

The cross-linking of multicomponent liquid crystals could be applied to the synthesis of nanometer-sized porous materials with a well-defined structure. In this work we demonstrate the template polymerization of columnar liquid crystals composed of the salts of a carboxylic acid and enantiopure 2-amino alcohols, and the application of one of them as a solid-state host. The salts of 3,4,5-tris(11-acryloyloxyundecyloxy)benzoic acid with (S)-2-amino-1-propanol and with (1R,2S)-norephedrine showed hexagonal and rectangular columnar liquid-crystalline structures, respectively. The successful application of gamma-ray-induced polymerization to the cross-linking of the liquid-crystalline salts, which was more advantageous than photoinduced polymerization from the standpoint of the retention of the original structural order in the gram-scale preparation of the polymers with a homogeneous columnar structure. The cross-linked polymer thus obtained from the gallic acid derivative and (1R,2S)-norephedrine was applicable as a heterogeneous host to capture amines from a guest solution through acid-amine interactions. When (1R,2S)-norephedrine was replaced with other amines through the guest-exchange reaction, a "template effect" was observed; the size and shape of the guests were determining factors for the efficiency of the guest exchange. The guest adsorption was found to proceed in an enantioselective manner when racemic 2-amino alcohols were used as guests, especially in the cases of substrates possessing a bulky substituent at the C1-position. The guest preference was again elucidated by the template effect, although the enantioselection mode was switched depending on the presence of a C2 substituent.     

Synthesis of 2-oxazolidinones by salen-Co-complexes catalyzed oxidative carbonylation of β-amino alcohols

2-Oxazolidinones are synthesized in high yield by oxidative carbonylation of β-amino alcohols using salen-Co(II)/NaI or salen-Co(III)-I as a catalyst and using CO as the carbonyl source. Studies of functional group compatibility using a series of substituted salen-Co(II) or salen-Co(III)-I complexes demonstrate a broad tolerance of functionality during the carbonylation reaction.     

Metal-free synthesis of 1,2-amino alcohols by one-pot olefin aziridination and acid ring-opening

A one-pot, two-step reaction comprising olefin aziridination and ring-opening of an aziridine intermediate to synthesize 1,2-amino alcohols has been developed. This reaction is suitable for several types of olefin. This methodology allows an efficient and highly stereoselective approach to various 1,2-amino alcohols, readily providing an alternative route to conventional vicinal amino alcohols.     

Diastereoselective syntheses of 2-amino propargyl alcohols. Chiral building blocks for enantiopure amino γ-lactones and 5-hydroxy-piperidinone derivatives

α-Dibenzylamino aldehydes, derived from the corresponding natural α-amino acids, react with metal acetylides to yield anti-amino propargyl alcohols in good yield and diastereomeric excess. syn Amino alcohols are prepared from the anti diastereoisomers and all of them are elaborated in few steps to enantiopure amino lactones and hydroxy-piperidin-2-ones.     

Synthesis of heavily substituted 1,2-amino alcohols in enantiomerically pure form

[reaction: see text] A simple and convenient methodology for the preparation of optically pure 2-amino-2-aryl-1,1-diphenylethanols is presented. Allylamine was found to produce the ring-opening of triaryloxiranes in a regioselective and a stereospecific fashion. Removal of the allyl protecting group provided the free 1,2-amino alcohols in enantiomerically pure form.     

2-ethynylaziridines as chiral carbon nucleophiles: stereoselective synthesis of 1,3-amino alcohols with three stereocenters via allenylindium reagents bearing a protected amino group

Allenylindium reagents bearing a protected amino group were effectively prepared from N-protected 3-alkyl-2-ethynylaziridines by treatment with InI in the presence of Pd(PPh(3))(4) and H(2)O. Stereoselective addition of the allenylindium to aliphatic or aromatic aldehydes affords 1,3-amino alcohols bearing three contiguous chiral centers: while 2,3-trans-2-ethynylaziridines yield syn,syn-2-ethynyl-1,3-amino alcohols predominantly, 2,3-cis-aziridines give anti,syn isomers selectively. Synthesis of highly substituted ethynylazetidines is also described.     

Enantioselective synthesis of β-amino alcohols and α-amino acids via a copper catalyzed addition of diorganozinc reagents to N-phosphinoylimines

Enantioenriched β-amino alcohols were prepared via an asymmetric addition of diethylzinc, catalyzed by the BozPHOS·Cu(I) complex, on in situ formed N-phosphinoylimines. The nature of the hydroxyl protecting groups was found to affect the enantioselectivities. Subsequent deprotection and oxidation of N-phosphinoyl β-amino alcohols afforded optically active α-amino acids (97% ee).     

Synthesis of sterically controlled chiral β-amino alcohols and their application to the catalytic asymmetric sulfoxidation of sulfides

Sterically hindered and enantiomerically pure β-amino alcohols 8a and 8b were prepared from the enantiomerically pure aziridine-2-carboxylic acid menthol ester 13. Vanadium complexes of the chiral Schiff-base ligands prepared from the β-amino alcohols catalyze an efficient enantioselective sulfoxidation of alkyl aryl sulfides, while enantioselectivities as high as 96% ee can be observed in the sulfoxidation of benzyl aryl sulfides.     

Synthesis of chiral, nonracemic methyleneaziridines derived from β-amino alcohols

An efficient three step process for the synthesis of chiral, nonracemic methyleneaziridines derived from homochiral β-amino alcohols is described. Methyleneaziridines 4a-e produced using this chemistry have been shown to possess high enantiomeric purities (≥ 95%ee).     

Chiral azo compounds: enantioselective synthesis and transformations into β-amino alcohols and α-amino acids with a quaternary stereocenter

Taking advantage of radical carboaminations producing azo compounds, a new chemo-enzymatic approach to enantiomerically enriched azo alcohols, β-amino alcohols and non-natural (aromatic) amino acids with a quaternary stereocenter is reported.     

A convenient preparation of β-amino alcohols from epoxides and halomagnesium alkylamides

Treatment of epoxides with halomagnesium alkylamides in THF affords the correspondinq β-amino alcohols in good yields.     

Synthesis of enantiopure azetidines: a route to new β-amino alcohols

β-Amino alcohols possessing an E vinylsilane moiety were cyclized in the presence of N-bromosuccinimide to afford diastereoisomerically pure polyfunctional azetidines. These azetidines were then transformed into enantiopure β-amino alcohols with a Z vinylic bromide moiety.     

A novel synthesis of cyclic α-amino aldehydes, amino alcohols, and α-amino acid methyl esters from cyclic ketones through sulfinylaziridines

Treatment of 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from cyclic ketones and chloromethyl p-tolyl sulfoxide in three steps in good yields, with N-lithio arylamines gave sulfinylaziridines in high yields. On treatment with N-lithio aniline or N-lithio p-chloroaniline, the sulfinylaziridines gave α-amino aldehydes in high yields. The α-amino aldehydes were converted to amino alcohols and α-amino acid methyl esters in moderate to good yields. This procedure offers an efficient method for synthesis of cyclic α-quaternary α-amino aldehydes, amino alcohols, and α-amino acid derivatives from cyclic ketones.     

A chiral ketone for enantioselective recognition of 1,2-amino alcohols

A novel auxillary chiral ketone has been designed, synthesized, and used to enantioselectively recognize 1,2-amino alcohols. This work proves that the keto group can serve as a chiral recognition center by imine formation supported by resonance assisted hydrogen bonding (RAHB).     

Polyoxygenated ketopinic-acid-derived γ-amino alcohols in the enantioselective diethylzinc addition to benzaldehyde

Three N,N-dialkylated γ-amino alcohols, specifically 10-(dialkylamino)isoborneols, with different grades of oxygenation in the nitrogen’s alkyl groups (alkoxyalkyl groups), have been obtained from commercial (+)-ketopinic acid and tested as chiral ligands for the enantioselective addition of diethylzinc to benzaldehyde, in order to evaluate the effect of polyoxygenation on the ligand’s catalytic activity. An interesting effect of the oxygen atoms on the ligand activity is observed. The observation is in agreement with two unique previous results on amino-acid-derived polyoxygenated β-amino alcohols. A noticeable dependence of the observed effect with the conformational flexibility of the polyoxygenated chains is also demonstrated. The effect is explained by a pincer role of the polyoxygenated dialkylamino moiety, activating and directing a diethylzinc molecule.