First preparative synthesis of a 3-acetamido-3,6-dideoxy-d-galactopyranose glycosyl donor via intramolecular cyclization of an epoxytrichloroacetimidate

2004 ◽  
Vol 45 (23) ◽  
pp. 4445-4448 ◽  
Author(s):  
Emiliano Bedini ◽  
Alfonso Iadonisi ◽  
Antonella Carabellese ◽  
Michelangelo Parrilli
Keyword(s):  
Intramolecular Cyclization ◽  
Preparative Synthesis ◽  
Glycosyl Donor

Concise Synthesis of GB22 by Endo-Selective Siloxycyclopropane Arylation

2019 ◽  
Author(s):  
Hannah E. Burdge ◽  
Takuya Oguma ◽  
Takahiro Kawajiri ◽  
Ryan Shenvi
Keyword(s):  
Intramolecular Cyclization ◽  
Cross Coupling ◽  
Building Blocks ◽  
Ring Expansion ◽  
Dual Catalysis ◽  
Acid Labile

<div><div><div><p>The first synthesis of GB22 was accomplished by a con- cise, modular route. Two building blocks converged in a novel sp3-sp2 attached-ring coupling that used Ir/Ni dual-catalysis to reverse the regioselectivity of siloxycy- clopropane arylation. This cross-coupling proved general to access β-substituted tetralones via ring-expansion of indanone-derived siloxycyclopropanes. The congested, bridging rings of the GB alkaloids were completed using an aluminum-HFIP complex that effected intramolecular cyclization of an acid-labile substrate.</p></div></div></div>

Concise Synthesis of GB22 by Endo-Selective Siloxycyclopropane Arylation

2019 ◽  
Author(s):  
Hannah E. Burdge ◽  
Takuya Oguma ◽  
Takahiro Kawajiri ◽  
Ryan Shenvi
Keyword(s):  
Intramolecular Cyclization ◽  
Cross Coupling ◽  
Building Blocks ◽  
Ring Expansion ◽  
Dual Catalysis ◽  
Acid Labile

<div><div><div><p>The first synthesis of GB22 was accomplished by a con- cise, modular route. Two building blocks converged in a novel sp3-sp2 attached-ring coupling that used Ir/Ni dual-catalysis to reverse the regioselectivity of siloxycy- clopropane arylation. This cross-coupling proved general to access β-substituted tetralones via ring-expansion of indanone-derived siloxycyclopropanes. The congested, bridging rings of the GB alkaloids were completed using an aluminum-HFIP complex that effected intramolecular cyclization of an acid-labile substrate.</p></div></div></div>

Ribonuclease a catalyzed preparative synthesis of dinucleoside monophosphates containing uridine analogues

1980 ◽  
Vol 45 (2) ◽  
pp. 611-616 ◽  
Author(s):  
Antonina P. Kavunenko ◽  
Antonín Holý
Keyword(s):  
Paper Chromatography ◽  
Ribonuclease A ◽  
Uv Spectra ◽  
Preparative Synthesis ◽  
Cyclic Phosphate ◽  
Dinucleoside Monophosphates

Preparative synthesis of dinucleoside monophosphates, catalyzed by ribonuclease A, is described. Uridine 2',3' -cyclic phosphate was used as a donor, the acceptors being uridine (Ia), N3-methyl-uridine (Ib), 5-methyluridine (Ic), 6-methyluridine (Id), 3-(β-D-ribofuranosyl)uracil (IIa), 1-methyl-3-(β-D-ribofuranosyl)uracil (IIb), 6-azauridine (III) and 6-methyl-2'-deoxyuridine (IV). The obtained compounds of the type UpN (where N is the nucleoside moiety I-IV) were characterized by paper chromatography, electrophoresis and UV-spectra.

Cyclopropyl→cyclobutyl rearrangement in intramolecular cyclization of 3,5-bridged B-secoandrostane-6,7(or 5,7)-diols and mass spectra of products

1982 ◽  
Vol 47 (8) ◽  
pp. 2280-2290 ◽  
Author(s):  
Helena Velgová ◽  
Jorga Smolíková ◽  
Antonín Trka ◽  
Antonín Vítek
Keyword(s):  
Intramolecular Cyclization ◽  
Mass Spectra ◽  
Acid Catalyzed

Acid-catalyzed intramolecular cyclization of 6,7-dihydroxy-3α,5-cyclo-6,7-seco-5α-androstan-17-one (VII), 5,7-dihydroxy-3,5-methylene-5,7-secoandrostan-17-one and 5,7-dihydroxy-3β,5-cyclo-5,7-seco-A-homo-5β-androstan-17-one (XIII) in benzene and dioxane was investigated. The main cyclization products were 3,5-methylene-6-oxaandrostan-17-one (I) and/or 3β,5-cyclo-6-oxa-A-homo-5β-androstan-17-one (VIII). In the case of VI and VII the ratio of I and VIII was solvent-dependent: in benzene more VIII was formed than in dioxane. The mass spectra of I and VIII were almost identical and corresponded to the structure VIII.

ChemInform Abstract: INTRAMOLECULAR CYCLIZATION IN REACTIONS OF BICYCLIC DIEPOXIDES WITH DIMETHYLAMINE

1985 ◽  
Vol 16 (9) ◽  
Author(s):  
L. I. KAS'YAN ◽  
N. S. ZEFIROV ◽  
N. V. STEPANOVA ◽  
L. E. SALTYKOVA ◽  
O. L. RYZHIK
Keyword(s):  
Intramolecular Cyclization

scholarly journals A One-Pot Approach to Novel Pyridazine C-Nucleosides

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2341
Author(s):  
Flavio Cermola ◽  
Serena Vella ◽  
Marina DellaGreca ◽  
Angela Tuzi ◽  
Maria Rosaria Iesce
Keyword(s):  
Organic Chemistry ◽  
Research Field ◽  
Modified Nucleosides ◽  
Protecting Groups ◽  
Coupling Reactions ◽  
One Pot ◽  
Pharmacological Interest ◽  
Classical Methodology ◽  
Glycosyl Donor ◽  
Neutral Conditions

The synthesis of glycosides and modified nucleosides represents a wide research field in organic chemistry. The classical methodology is based on coupling reactions between a glycosyl donor and an acceptor. An alternative strategy for new C-nucleosides is used in this approach, which consists of modifying a pre-existent furyl aglycone. This approach is applied to obtain novel pyridazine C-nucleosides starting with 2- and 3-(ribofuranosyl)furans. It is based on singlet oxygen [4+2] cycloaddition followed by reduction and hydrazine cyclization under neutral conditions. The mild three-step one-pot procedure leads stereoselectively to novel pyridazine C-nucleosides of pharmacological interest. The use of acetyls as protecting groups provides an elegant direct route to a deprotected new pyridazine C-nucleoside.

scholarly journals Easily accessible non-aromatic heterocycles with handles: 4-Bromo-2,3-dihydrofurans from 1,2-dibromohomoallylic alcohols

2021 ◽  
Author(s):  
Jason An ◽  
Jose Intano ◽  
Alissa Richard ◽  
Taehyun Kim ◽  
Jose Gascon ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Aromatic Heterocycles

The first general preparation of 4-bromo-2,3-dihydrofurans is reported. These non-aromatic heterocyles containing a useful coupling handle are accessed via Cu-catalyzed intramolecular cyclization of 1,2-dibromohomoallylic alcohols, which are themselves available in...

Facile intramolecular cyclization of an olefinic grignard reagent

1966 ◽  
Vol 7 (36) ◽  
pp. 4297-4301 ◽  
Author(s):  
Herman G. Richey ◽  
Thomas C. Rees
Keyword(s):  
Intramolecular Cyclization ◽  
Grignard Reagent

CF3SOCl-Promoted Intramolecular Cyclization of β-Diketones: An Efficient Synthesis of Flavones

Tetrahedron ◽  
2021 ◽  
pp. 132226
Author(s):  
Dong-Wei Sun ◽  
Yong-Yan Zhou ◽  
Min Jiang ◽  
Tang Nian ◽  
Jin-Tao Liu
Keyword(s):  
Intramolecular Cyclization ◽  
Efficient Synthesis

scholarly journals Cold-Active β-Galactosidases: Insight into Cold Adaption Mechanisms and Biotechnological Exploitation

Marine Drugs ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 43
Author(s):  
Marco Mangiagalli ◽  
Marina Lotti
Keyword(s):  
Low Temperature ◽  
Molecular Mechanisms ◽  
Building Blocks ◽  
Cold Active ◽  
Cold Adaption ◽  
Glycosyl Donor ◽  
Pharmaceutical Industries ◽  
Biotechnological Processes ◽  
Hydrolysis Of ◽  
Insight Into

β-galactosidases (EC 3.2.1.23) catalyze the hydrolysis of β-galactosidic bonds in oligosaccharides and, under certain conditions, transfer a sugar moiety from a glycosyl donor to an acceptor. Cold-active β-galactosidases are identified in microorganisms endemic to permanently low-temperature environments. While mesophilic β-galactosidases are broadly studied and employed for biotechnological purposes, the cold-active enzymes are still scarcely explored, although they may prove very useful in biotechnological processes at low temperature. This review covers several issues related to cold-active β-galactosidases, including their classification, structure and molecular mechanisms of cold adaptation. Moreover, their applications are discussed, focusing on the production of lactose-free dairy products as well as on the valorization of cheese whey and the synthesis of glycosyl building blocks for the food, cosmetic and pharmaceutical industries.

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