- Ether-directed, stereoselective aza-claisen rearrangements: Synthesis of the piperidine alkaloid, α-conhydrine
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Equation presented A new approach for the stereoselective synthesis of the piperidine alkaloid (+)-α-conhydrine and its pyrrolidine derivative has been developed using a palladium(II)-catalyzed, MOM-ether-directed aza-Claisen rearrangement and ring-closing metathesis to effect the key steps.
- Jamieson, Andrew G.,Sutherland, Andrew
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- Stereoselective syntheses of (+)-α- and (-)-β-conhydrine from L-aspartic acid
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An efficient synthesis of (+)-α-conhydrine 1 and (-)-β- conhydrine 2 has been achieved by diastereoselective alkylation of an amino aldehyde derivative 7 with ethylmagnesium bromide or diethylzinc.
- Pandey, Satyendra Kumar,Kumar, Pradeep
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- Stereoselective addition of Grignard reagents to sulfinimines derived from tartrate diol (threitol): Generation of chiral building blocks for the collective total synthesis of lentiginosine, conhydrine and methyldihydropalustramate
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A systematic investigation of the addition of Grignard reagents to sulfinimines derived from tartaric acid diol was undertaken. It was observed that the chirality of the inherent tartrate moiety influences the diastereoselectivity of the resultant sulfinamides formed in the reaction. The formed products serve as excellent building blocks for the synthesis of natural products. This has been demonstrated in the collective total synthesis of lentiginosine, (+)-α-conhydrine and methyldihydropalustramate.
- Prasad, Kavirayani R.,Rangari, Vipin Ashok
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- Stereoselective synthesis of (-)-α-conhydrine and its pyrrolidine analogue
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The stereoselective synthesis of (-)-α-conhydrine and its pyrrolidine analogue was achieved from readily available D-erythronolactone. The key step of this synthesis includes a highly regioselective and diastereoselective addition of chlorosulfonyl isocyanate to 1,2-anti-dibenzyl ether to afford the 1,2-anti-amino alcohol. The total synthesis of (-)-α-conhydrine and its pyrrolidine analogue starting from readily available D-erythronolactone was achieved via the regioselective and diastereoselective allylic amination of anti-1,2-dibenzyl ether by using chlorosulfonyl isocyanate.
- Dong, Guang Ri,Hong, Seungmin,Kim, Seung In,Kim, In Su,Jung, Young Hoon
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p. 4200 - 4205
(2012/10/07)
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- Stereoselective total synthesis of (-)-β-conhydrine and (+)-α-conhydrine
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We have carried out the stereoselective synthesis of (-)-β- conhydrine and (+)-α-conhydrine, two bioactive α-hydroxyalkyl-substituted piperidines, using the commercially available and inexpensive amino alcohol (S,S)-(+)-pseudoephedrine as chiral auxiliary. The key step of this synthesis relies on new methodology previously developed in our group, consisting of the chemo- and diastereoselective addition of Grignard reagents across the C=N bond of α-iminoglyoxylamides derived from (S,S)-(+)-pseudoephedrine followed by the selective monoaddition of organolithium reagents to the carbamoyl group, leading to the formation of enantioenriched -amino ketones. Georg Thieme Verlag Stuttgart New York.
- Reyes, Efraim,Ruiz, Nerea,Vicario, Jose L.,Badia, Dolores,Carrillo, Luisa
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p. 443 - 450
(2011/04/16)
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- Enantioselective Synthesis of (+)-α-Conhydrine and (-)-Sedamine by L-ProlineCatalysed α-Aminooxylation
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An efficient organocatalytic approach to the enantioslective synthesis of two important piperidine alkaloids, namely (+)α-conhydrine (98% ee) and (-)-sedamine (95 % ee), by L-pro-line-catalysed α-aminooxylation of aldehydes has been developed. The strategy involves an intramolecular cyclization to construct the piperidine core.
- Shaikh, Tanveer Mahamadali,Sudalai, Arumugam
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experimental part
p. 3437 - 3444
(2010/08/20)
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- A straightforward synthesis of conhydrine by hetero Diels-Alder strategy mediated by microwaves
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Synthesis of optically active conhydrines has been achieved by hetero Diels-Alder cycloaddition assisted by microwaves.
- Bandini, Elisa,Corda, Giulia,D'Aurizio, Antonio,Panunzio, Mauro
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supporting information; experimental part
p. 933 - 934
(2010/05/18)
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- Highly enantioselective synthesis of chiral cyclic amino alcohols and conhydrine by ruthenium-catalyzed asymmetric hydrogenation
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A highly efficient enantio- and diastereoselective synthesis of chiral cis-β-N-alkyl/arylamino cyclic alcohols has been realized by asymmetric hydrogenation of racemic α-amino cyclic ketones via DKR catalyzed by [RuCl2((S)-Xyl-SDP)((R,R)-DPEN)]. The enantioselectivities of the reaction were up to 99.9% ee with 99:1 cis-selectivities. A practical catalytic asymmetric synthesis of all four isomers of conhydrine was also developed.
- Liu, Sheng,Xie, Jian-Hua,Li, Wei,Kong, Wei-Ling,Wang, Li-Xin,Zhou, Qi-Lin
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supporting information; experimental part
p. 4994 - 4997
(2009/12/28)
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- An approach towards the total synthesis of (+)-epiquinamide and (+)-α-conhydrine from Garner aldehyde
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A short and stereoselective route for the synthesis of 1-hydroxyquinolizidine, an advanced synthetic intermediate for the total synthesis of (+)-epiquinamide is presented. The key synthetic steps involve diastereoselective nucleophilic addition on l-serin
- Srivastava, Ajay Kumar,Das, Sanjit Kumar,Panda, Gautam
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experimental part
p. 5322 - 5327
(2009/12/01)
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- Metal-dependent reaction tuning with cyclopentylmetal reagents: Application to the asymmetric synthesis of (+)-α-conhydrine and (S)-2-cyclopentyl-2- phenylgrycolic acid
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The reaction profile of the cyclopentyl organometallic reagents with the aliphatic ketones can be tuned to reduction or addition by changing the metal atom. Cyclopentylmagnesium bromide (CPMB) reduces aromatic and aliphatic aldehydes and ketones to the corresponding alcohols without any C-C bond formation and shows good diastereoselectivity in the reduction of the substituted cyclic and polycyclic ketones as well as chiral α-oxygenated aliphatic ketones. However, in the presence of 10 mol% of ZnClα 2, the cyclopentylmagnesium halides follow a normal Grignard addition to the ketones to give tertiary alcohols with complete diastereoselectivity. The reductive as well as the addition protocols were used for the asymmetric synthesis of two medicinally important compounds, (+)-α-conhydrine and (S)-2-cyclopentyl-2-phenylglycolic acid.
- Roy, Siddharth,Sharma, Anubha,Mula, Soumyaditya,Chattopadhyay, Subrata
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experimental part
p. 1713 - 1722
(2009/09/07)
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- A highly stereocontrolled route to 2-(2′-oxiranyl)piperidines and pyrrolidines: enantioselective synthesis of (+)-α-conhydrine
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The first enantio- and diastereoselective approach to both 2-(2′-oxiranyl)piperidines and to 2-(2′-oxiranyl)pyrrolidines is reported. The method relies on the Sharpless asymmetric epoxidation of allyl alcohols as the sole source of chirality, and involves as the key step the base-mediated cyclization of (α-aminoalkyl)oxiranes functionalized at the ε{lunate} (or δ) position. The asymmetric synthesis of (+)-α-conhydrine illustrates the applicability of this strategy to the preparation of biologically active 2-(1-hydroxyalkyl)piperidine alkaloids.
- Rodríguez, Dídac,Picó, Anna,Moyano, Albert
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scheme or table
p. 6866 - 6869
(2009/04/07)
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- Short and efficient asymmetric synthesis of (-)-α-conhydrine
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(Chemical Equation Presented) The short and efficient synthesis of (-)-α-conhydrine was accomplished with 41% overall yield in seven steps and high diastereo- and enantioselectivity. The anti-stereochemistry of the two stereogenic centers has been confirmed by the single-crystal X-ray analysis of an intermediate.
- Voituriez, Arnaud,Ferreira, Franck,Chemla, Fabrice
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p. 5358 - 5361
(2008/02/08)
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- Synthesis of α-conhydrine
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A synthesis of α-conhydrine has been achieved from trans-(2S,4R)-4-hydroxyproline via diastereoselective Grignard addition, regioselective Baeyer-Villiger reaction, and ring-closing metathesis as the key steps.
- Chang, Meng-Yang,Kung, Yung-Hua,Chen, Shui-Tein
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p. 10843 - 10848
(2007/10/03)
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- A concise enantioselective synthesis of (+)-α-conhydrine
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A short step synthesis of (+)-α-conhydrine was achieved employing a kinetic resolution of 2-(1-hydroxypropyl)pyridine with lipase PS and a chelation-controlled diastereoselective reduction of pyridine ring as key reactions.
- Nagata, Kazuhiro,Toriizuka, Yosuke,Itoh, Takashi
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p. 107 - 109
(2007/10/03)
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- Asymmetric synthesis of (-)-α-conhydrine
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The enantioselective synthesis of (-)-α-conhydrine has been achieved by two different synthetic routes. The key steps include Sharpless asymmetric dihydroxylation, regioselective opening of a cyclic sulfate and Wittig olefination.
- Kandula, Subba Rao V.,Kumar, Pradeep
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p. 3268 - 3274
(2007/10/03)
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- Enantioselective synthesis of (-)-α-conhydrine via cyclic sulfate methodology
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An asymmetric synthesis of (-)-α-conhydrine is described using the Sharpless asymmetric dihydroxylation and the regiospecific nucleophilic opening of a cyclic sulfate as the key steps.
- Kandula, SubbaRao V.,Kumar, Pradeep
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p. 1957 - 1958
(2007/10/03)
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- Asymmetric synthesis and structural assignment of (-)-α-conhydrine
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The first asymmetric synthesis of the conium alkaloid (-)-α-conhydrine is reported. Starting from a protected glycol aldehyde hydrazone as chiral precusor, a short route based on our α-alkylation/1,2-addition methodology has been developed. After cleavage of the auxiliary and simultaneous deprotection, the concluding ring closure is accomplished under reductive amination conditions. The title compound is obtained in moderate overall yield and in excellent diastereo- and enantiomeric excess (d.e., e.e. >96%). Single-crystal X-ray crystallography as well as 1H NMR NOE experiments confirm the expected relative and absolute (2R,7S)-configuration of the product.
- Enders, Dieter,Nolte, Bert,Raabe, Gerhard,Runsink, Jan
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p. 285 - 291
(2007/10/03)
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- Asymmetric synthesis of erythro- and threo-2-(1-hydroxyalkyl)piperidines via iodocyclocarbamation of 1-acyl-2-alkenyl-1,2,3,6-tetrahydropyridines
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An iodocyclocarbamation procedure has been developed for the stereoselective preparation of erythro- and threo-2-(1- hydroxyalkyl)piperidines. This methodology was utilized in the asymmetric synthesis of two piperidine alkaloids, (+)-α-conhydrine and (+)-β- conhydrine. (C) 2000 Elsevier Science Ltd.
- Comins, Daniel L.,Williams, Alfred L.
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p. 2839 - 2842
(2007/10/03)
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- Enantiospecific synthesis of optically active natural (+)-conhydrine from (S,S)-tartaric acid
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The first enantiospecific synthesis of (+)-conhydrine, one of the poisonous alkaloids of the hemlock was achieved via partial ring opening of 6,8-dioxabicyclo[3.2.1]-octane skeleton prepared from (S,S)-tartaric acid
- Masaki,Imaeda,Nagata,Oda,Ito
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p. 6395 - 6396
(2007/10/02)
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