Stereogenic boron in 2-amino-1,1-diphenylethanol-based boronate–imine and amine complexes

• Sebastian Schlecht,
• Walter Frank and
• Manfred Braun

Beilstein J. Org. Chem. 2011, 7, 615–621, doi:10.3762/bjoc.7.72

• known procedure [20], the amino alcohol 5 was readily accessible from methyl glycinate hydrochloride by the reaction with excess phenylmagnesium bromide. Subsequent condensation with 1-formyl-2-naphthol (6) gave the imine 7 in 87% yield (Scheme 2). In order to generate the boronate–imine complex 8, the

• . HPLC was performed with the chiral column CHIRALPAK IB. Toluene was freshly distilled from sodium under a nitrogen atmosphere. 1-{[(2-Hydroxy-2,2-diphenylethyl)imino]methyl}naphthalen-2-ol (7) A mixture of amino alcohol 5 (0.427 g, 2.00 mmol), naphthaldehyde 6 (0.379 g, 2.20 mmol), and sodium sulfate

Application of the diastereoselective photodeconjugation of α,β-unsaturated esters to the synthesis of gymnastatin H

• Ludovic Raffier and
• Olivier Piva

Beilstein J. Org. Chem. 2011, 7, 151–155, doi:10.3762/bjoc.7.21

• enantioselective versions. Starting from α-substituted esters 3 in the presence of a catalytic amount of an enantiomerically pure bicyclic amino alcohol 4 – derived from camphor –, the protonation of the prochiral photodienol can be achieved with an ee up to 91% [5]. This value is one of the highest values

• ]. In this context, we have considered an alternative synthetic route to the fatty acid common to all gymnastatins according to a photoisomerisation–diastereoselective protonation sequence involving catalytic amounts of an achiral organocatalyst (e.g., amino alcohol 4b). Our goal was to describe the

α,β-Aziridinylphosphonates by lithium amide-induced phosphonyl migration from nitrogen to carbon in terminal aziridines

• David. M. Hodgson and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2010, 6, 978–983, doi:10.3762/bjoc.6.110

• or BF3•Et2O in CH2Cl2; aminolytic kinetic resolution [12][38]), and use of (Me3)SiHNPO(OEt)2 [39] also proved ineffective. A convenient asymmetric access was eventually developed, starting with ring-opening of commercially available (R)-1,2-epoxybutane (15) using ammonia, which gave β-amino alcohol

Oxalyl retro-peptide gelators. Synthesis, gelation properties and stereochemical effects

• Janja Makarević,
• Milan Jokić,
• Leo Frkanec,
• Vesna Čaplar,
• Nataša Šijaković Vujičić and
• Mladen Žinić

Beilstein J. Org. Chem. 2010, 6, 945–959, doi:10.3762/bjoc.6.106

• represents the major organizational element in the gel assemblies of both, bis(amino acid)- and bis(amino alcohol)oxalamides, and also has the major influence on their organization in the solid state [55][56][57][58][59][60]. In addition, the latter gelators tend to exhibit layered organization in their gel

• strongly influence both, gelation effectiveness and the morphology characteristics of gel network. Chiral bis(amino acid)-(I) and bis(amino alcohol)-(II)-oxalamide gelators. TEM images (PWK staining) of: (S,S)-1a H2O/DMSO gel. TEM images (PWK staining) of: (S,R)-1a H2O/DMSO gel. TEM images (PWK staining

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• catalytic transfer hydrogenation. Accordingly, 4-nitroanisole was reduced under microwave conditions to give 4-aminoanisole which reacted immediately with the diglycidyl ether of bisphenol A in an addition polymerization reaction to yield oligo(amino alcohol)s. The hydroxy groups of the new formed oligomers

• former work on the formation of hyperbranched epoxide-amine adducts via microwave-assisted heterogeneous catalytic transfer hydrogenation [22], we report herein the synthesis of an linear oligo(amino alcohol). The hydroxy groups of the latter were then used as an initiator for the ring-opening

• by the complete disappearance of the absorption band at 911 cm−1 associated with the C–H stretching vibration of the epoxide group. Furthermore, the formation of amino alcohol units was confirmed by the appearance of a broad band in the range of 3600–3150 cm−1 with a maximum at 3370 cm−1

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Concise methods for the synthesis of chiral polyoxazolines and their application in asymmetric hydrosilylation

• Wei Jie Li,
• Zun Le Xu and
• Sheng Xiang Qiu

Beilstein J. Org. Chem. 2010, 6, No. 29, doi:10.3762/bjoc.6.29

• analytical grade. Syntheses of polyoxazoline ligands 3,4-Dihydroxy-2,5-bis(4-substituted-oxazolin-2-yl)furan Method A: 3,4-Dihydroxyfuran-2,5-dicarboxylic acid (0.75 g, 4.0 mmol), the chiral amino alcohol (8.8 mmol) and toluene (40 mL) were placed in a three-neck flask, fitted with a water segregator, a

• desired compound. Method B: 0.87 g (4.0 mmol) of dimethyl-3,4-dihydroxyfuran-2,5-dicarboxylate, 8.0 mmol of the chiral amino alcohol and 40 mL of toluene were added to a three-neck flask equipped with a water segregator, a reflux condenser and a magnetic stirring bar. The mixture was heated under reflux

Synthesis of a new class of aminocyclitol analogues with the conduramine D-2 configuration

• Latif Kelebekli,
• Yunus Kara and
• Murat Celik

Beilstein J. Org. Chem. 2010, 6, No. 15, doi:10.3762/bjoc.6.15

• diols in the presence of p-toluenesulfonyl isocyanate for the introduction of the amino alcohol functionality. We are currently interested in the synthesis of cyclitols and their derivatives [25]. As a part of our program directed towards the synthesis of potential glycosidase inhibitors we used a

• % yield. The introduction of the amino alcohol functionality was achieved by a regio- and stereoselective Pd(0) catalyzed reaction of diol 11 and TsNCO [32]. Thus treatment of the cis-diol 11 in THF with 2 equiv of p-toluenesulfonyl isocyanate gave the corresponding bis-carbamate 12 which was subsequently

Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups

• Julien Rolland,
• Xacobe C. Cambeiro,
• Carles Rodríguez-Escrich and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2009, 5, No. 56, doi:10.3762/bjoc.5.56

• flow system for the synthesis of enantioenriched diarylmethanols from aldehydes is described. The system uses an amino alcohol-functionalized polystyrene resin as the catalyst, and the arylating agent is conveniently prepared by transmetallation of triarylboroxins with diethylzinc. Keywords

• reaction, although usually at the cost of low catalytic activity, high catalytic loadings being required for the achievement of satisfactory yields [14][15]. In contrast, β-amino alcohol 1 (Figure 2), developed in our laboratory [16], showed high activity and enantioselectivity in the ethylation [16

• mmol) in toluene (33 mL), was connected to one of the pumps, at 0.12 mL·min−1, while toluene (0.12 mL·min−1) was kept in the other one, and the column was cooled down to 10 °C. These conditions were kept for a further 1 h, in order to form the amino alcohol-Zn complex. Then, a 0.61 M solution of

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• flow process for the addition of diethylzinc to various aldehydes was described recently (Scheme 4) [27]. Reagent solutions were fed by piston-pump driven flow through a fritted column packed with chiral amino-alcohol functionalized Merrifield resin 9. Under optimal conditions (10 °C, a flow rate of

• drops during flow-through that can often be problematic with gel-type resins. The flexibility and ease for adjusting porosity, composition and shape of these materials is an additional advantage [37][38]. The monolith-supported chiral amino alcohol catalyst 29 has been developed for the enantioselective

• flow. Asymmetric synthesis of ß-lactams. α-Chlorination of acid chlorides in flow. Asymmetric Michael reaction in continuous flow. Enantioselective addition of Et2Zn to benzaldehyde using monolithic chiral amino alcohol. Continuous-flow hydrolytic dynamic kinetic resolution of epibromohydrin (32

(−)-Complanine, an inflammatory substance of marine fireworm: a synthetic study

• Kazuhiko Nakamura,
• Yu Tachikawa and
• Daisuke Uemura

Beilstein J. Org. Chem. 2009, 5, No. 12, doi:10.3762/bjoc.5.12

• was then subjected to acidic deprotection to afford the diol 6 in 43% yield (2 steps). The primary alcohol was converted into the azide via the mesylate (79%), which was then successfully converted into the corresponding amino alcohol 7 (78%). From a spectral perspective, the amino alcohol 7 was

• , CH3CN, rt, 24 h) [9]. A reaction occurred between the amino alcohol and the activated ester (2.0 equiv) in MeOH to give the desired (−)-complanine in 44% yield. The synthesized product was identical to the natural material in all its spectral data, including optical rotation ([α]D20 = −9.9 (c 0.12, H2O

• )). The configuration of the hydroxy-substituted carbon atom was determined to be R. The configuration is comparable to that of the related compound, obscuraminol, isolated from an ascidian from Tarifa Island, Spain. Obscuraminol possesses a vic-amino alcohol and an unsaturated carbon chain; its absolute

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• synthesis before the introduction of other incompatible functional groups (lactam, thiolactam, enaminone). The only feasible option was to go back to the chiral amine (+)-14, reduction of which with lithium aluminium hydride gave the unstable amino alcohol (+)-30 in 97% yield as long as the amine was added

• slowly to a stirred suspension of the hydride in diethyl ether (Scheme 4). If the order of addition were reversed, the best yield obtained was 48%. The amino alcohol was protected as its tert-butyl(dimethyl)silyl ether (−)-31 (99%) before hydrogenolysis of the benzyl groups over Pearlman's catalyst in

A divergent asymmetric approach to aza-spiropyran derivative and (1S,8aR)-1-hydroxyindolizidine

• Jian-Feng Zheng,
• Wen Chen,
• Su-Yu Huang,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2007, 3, No. 41, doi:10.1186/1860-5397-3-41

• procedure, namely, N-debenzylation/O-mesylation/Boc-cleavage/cyclization, and O-debenzylation. Alternatively, amino alcohol 8 was mesylated and the resultant mesylate 12 was subjected to hydrogenolytic conditions, which gave (1S,8aR)-1-hydroxyindolizidine (ent-3) in 60% overall yield from 8. Conclusion By

• -cleavage/cyclication, and O-debenzylation. In searching for a more concise method, amino alcohol 8 was mesylated (MsCl, NEt3, 0 °C) and the resultant labile mesylate 12 was subjected to catalytic hydrogenolysis (H2, l atm, 10% Pd/C, r.t.), which gave (1S,8aR)-1-hydroxyindolizidine (ent-3) in 60% overall

• . Stereoselective synthesis of (1S,8aR)-1-hydroxyindolizidine (ent-3). One-pot synthesis of ent-3 from amino alcohol 8. Supporting Information Supporting Information File 94: Experimental. Experimental procedures for the synthesis of all compounds described, and characterization data for the synthesized compounds

The enantiospecific synthesis of (+)-monomorine I using a 5-endo- trig cyclisation strategy

• Malcolm B. Berry,
• Donald Craig,
• Philip S. Jones and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2007, 3, No. 39, doi:10.1186/1860-5397-3-39

• synthesis of (+)-monomorine I, the initial target, pyrrolidine 22, was prepared. Commercially available D-norleucine was reduced to the amino alcohol 17. [19] This was then converted into the benzoyl-protected aminosulfone 20 via the diphenylphosphinylaziridine 18, which was ring-opened to give 19, followed

Pd-catalysed [3 + 3] annelations in the stereoselective synthesis of indolizidines

• Olivier Y. Provoost,
• Andrew J. Hazelwood and
• Joseph P. A. Harrity

Beilstein J. Org. Chem. 2007, 3, No. 8, doi:10.1186/1860-5397-3-8

• modification of the route described by Righi and co-workers [11]. Accordingly, tosyl protection of (R)-serine 5 followed by esterification and TBDPS-protection provided 6 in good overall yield. Ester reduction was carried out conveniently on multigram scale using LiBH4 to give an amino alcohol that was

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• hands, we next turned to the obtention of C8-aminocyclitols. Thus, reduction of the azido group of 11 by dihydrogen in the presence of palladium black in ethyl acetate (Scheme 3) afforded the amino-alcohol 13 which could be submitted to acidic hydrolysis of the O-protective groups to give, after

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• configurations may be easily prepared. Our synthetic strategy is outlined in Scheme 1. We have previously shown that the configuration of 1,3-amino alcohol derivatives, such as 10, may be controlled by the addition of a lithium enolate to an N-sulfinyl imine (→ 9, for example) and diastereoselective reduction

• (Scheme 2).[24][25][26][27][28][29][30][31][32] Two-directional[33] oxidative ring expansion of 1,3-difuryl 1,3-amino alcohol derivatives 4 would yield a densely functionalised bis-enone which would be ripe for further functionalisation. The term "two-directional synthesis" is usually used to describe the

• materials were prepared from the 1,3-amino alcohol derivatives 1,3syn- and 1,3anti-10 (Scheme 6). Treatment of the difuryl 1,3-sulfinimido alcohols 1,3syn- and 1,3anti-10 with NBS in buffered THF-water precipitiated sulfonamide oxidation and two-directional ring expansion of both furan rings;[50] the crude