Preparative and Stereoselective Synthesis of the Versatile Intermediate for Carbocyclic Nucleosides:  Effects of the Bulky Protecting Groups to Enforce Facial Selectivity

2004 ◽  
Vol 69 (7) ◽  
pp. 2634-2636 ◽  
Author(s):  
Won Jun Choi ◽  
Hyung Ryong Moon ◽  
Hea Ok Kim ◽  
Byul Nae Yoo ◽  
Jeong A Lee ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Protecting Groups ◽  
Carbocyclic Nucleosides ◽  
Facial Selectivity

ChemInform Abstract: Stereoselective Synthesis of 1,3-Disaccharides Through Diels-Alder Reactions. Part 2. Convenient Protecting Groups for Heterodienes and Conformational Evaluations.

ChemInform ◽  
2009 ◽  
Vol 40 (39) ◽  
Author(s):  
Gabriele Gabrielli ◽  
Fabrizio Melani ◽  
Sara Bernasconi ◽  
Carlotta Lunghi ◽  
Barbara Richichi ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Diels Alder ◽  
Protecting Groups

Stereoselective Synthesis of 1,3-Disaccharides through Diels-Alder Reactions: Part 2[ ]: Convenient Protecting Groups for Heterodienes and Conformational Evaluations

2009 ◽  
Vol 28 (3) ◽  
pp. 124-141 ◽  
Author(s):  
Gabriele Gabrielli ◽  
Fabrizio Melani ◽  
Sara Bernasconi ◽  
Carlotta Lunghi ◽  
Barbara Richichi ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Diels Alder ◽  
Protecting Groups

Synthesis of Carba Analogues of Deoxy-4-C-(hydroxymethyl)pentofuranoses, Intermediates in the Synthesis of Carbocyclic Nucleosides

1998 ◽  
Vol 63 (12) ◽  
pp. 2044-2064 ◽  
Author(s):  
Hubert Hřebabecký ◽  
Milena Masojídková ◽  
Antonín Holý
Keyword(s):  
Allyl Alcohol ◽  
Major Product ◽  
Protecting Groups ◽  
Carbocyclic Nucleosides ◽  
Lithium Aluminium Hydride ◽  
Lithium Aluminium ◽  
Benzoyl Group ◽  
Glucose Reduction ◽  
Hydroxy Groups

Racemic dimethyl 4-methoxy- (11 and 12), diallyl 4-allyloxy- (13 and 14) and dimethyl 4-(ethylsulfanyl)-2-hydroxycyclopentane-1,1-dicarboxylates (15 and 16) were prepared by base-catalyzed addition of methanol, allyl alcohol and ethylsulfane, respectively, to dimethyl (4-oxobut-2-en-1-yl)malonate (6). Deallylation of 13 and 14 afforded 4-hydroxycyclopentanes 27 and 28. Reduction of 11-16 with lithium aluminium hydride gave the corresponding 4-substituted 2,2-bis(hydroxymethyl)cyclopentanols. Dimethyl (2S,3S,4R)-, (2R,3S,4R)-3-benzyloxy-4-formyloxy-2-hydroxycyclopentane-1,1-dicarboxylates (35, 36) and dimethyl (2S,3S,4R)-, (2R,3S,4R)-3-benzyloxy-2-benzoyloxy-4-methoxycyclopentane-1,1-dicarboxylates (39, 40) were synthesized starting from D-glucose. Reduction of dimethyl cyclopentane-1,1-dicarboxylates 39 and 40 with lithium aluminium hydride, benzoylation of the formed hydroxy derivatives, hydrogenolysis of benzyl groups, conversion of the liberated hydroxy groups into dithiocarbonates and their reduction with tributylstannane afforded, after removal of the protecting groups, (2R,4R)-1,1-bis(hydroxymethyl)-4-methoxycyclopentan-2-ol ((2R,4R)-17) and (3R,4R)-1,1-bis(hydroxymethyl)-4-methoxycyclopentan-3-ol (51). Reduction of a mixture of esters 35 and 36 gave (2R,3R)-2-benzyloxy-5-(hydroxymethyl)hexane-1,3,6-triol (52) as the major product and (2R,3S,4R)-3-benzyloxy-1,1-bis(hydroxymethyl)cyclopentane-2,4-diol (53) as the minor product. The latter was converted into (3R,4R)-1,1-bis(hydroxymethyl)cyclopentane-3,4-diol (58). 3-Deoxycarba analogues 51 and 58 arose by migration of benzoyl group in the preparation of the dithiocarbonates.

scholarly journals A General Synthetic Approach to Hydroquinone Meroterpenoids: Stereoselective Synthesis of (+)-(S)-Metachromin V and Alliodorol

2014 ◽  
Vol 9 (3) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Stefano Serra ◽  
Alessandra A. Cominetti ◽  
Veronica Lissoni
Keyword(s):  
Chemical Structure ◽  
Stereoselective Synthesis ◽  
Coupling Reaction ◽  
Protecting Groups ◽  
Magnesium Bromide ◽  
Synthetic Approach ◽  
Cross Coupling Reaction ◽  
New Synthesis ◽  
First Time ◽  
Very High

A new general synthetic approach to hydroquinone meroterpenoids is here described. The framework of the aforementioned natural compounds was built up through the Li2CuCl4 catalysed cross coupling reaction of the 4-substituted-( E)-prenyl acetates 9 with 2,5-bis(benzyloxy)phenyl magnesium bromide 8 as a key step. The latter sp3-sp2 coupling affords the products in good chemical yields and in very high stereoisomeric purity. A further key step of the present synthetic method consists of the removal of the benzylic protecting groups by a very mild procedure based on the use of lithium naphthalenide. The latter reagent, in combination with aliphatic dialkylamines, is able to cleave all the benzylic protecting groups leaving unaffected the polyenic moieties. By these means, we devised a new synthesis of the natural hydroquinone geranylhydroquinone, farnesylhydroquinone, metachromin V and alliodorol. In addition, the marine meroterpenoid, (+)-( S)-metachromin V, was synthesized for the first time; its chemical structure was confirmed and its absolute configuration was unambiguously assigned.

An Efficient and Concise Synthesis of α-Galactosylceramide

Synlett ◽  
2020 ◽  
Author(s):  
Daniela Imperio ◽  
Laura Morelli ◽  
Federica Compostella ◽  
Luigi Panza
Keyword(s):  
Stereoselective Synthesis ◽  
Protecting Groups ◽  
Synthetic Strategy ◽  
Key Features ◽  
Glycosylation Reaction

AbstractA concise and stereoselective synthesis of α-galactosylceramide (α-GalCer) is described. The key features of the synthetic strategy are the use of a phytosphingosine in which the amine is masked as a tetrachlorophthalimide and the diol as an isopropylidene acetal, and the galactosyl donor is protected as a 4,6-benzylidene to improve the α selectivity of the glycosylation reaction. The pattern of protecting groups on the donor and the acceptor have proven to give an excellent match of reactivity, allowing the glycosylation reaction to take place stereoselectively. The overall synthesis gave α-GalCer in good yields and in few steps.

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