scholarly journals Cyclization into Hydrindanes Using Samarium Diiodide: Stereochemical Features Depending on the Protecting Group

2016 ◽  
Vol 11 (8) ◽  
pp. 1934578X1601100
Author(s):  
Masakazu Sono ◽  
Yukiko Nishibuchi ◽  
Norihito Yamaguchi ◽  
Motoo Tori
Keyword(s):  
Hydroxy Group ◽  
Samarium Diiodide ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Bicyclic Compounds

Monocyclic compounds bearing ketone and enone moieties in the same molecule can be cyclized to bicyclic compounds initiated by samarium diiodide. The stereochemistry of the products depended on the reaction conditions and also the protecting group of the hydroxy group existed in the molecule. A cyclization mechanism is discussed.

Synthesis of (15E)-17β-hydroxy-5α-androstane-3,15-dione 15-[O-(Carboxymethyl)]oxime, New Hapten for Dihydrotestosterone (17β-hydroxy-5α-androstan-3-one)

1997 ◽  
Vol 62 (10) ◽  
pp. 1642-1649 ◽  
Author(s):  
Ivan Černý ◽  
Tereza Slavíková ◽  
Vladimír Pouzar
Keyword(s):  
Hydroxy Group ◽  
Carboxy Group ◽  
Title Compound ◽  
Oxidative Cleavage ◽  
Hydroxy Derivative ◽  
Borohydride Reduction ◽  
Protecting Group ◽  
Free Hydroxy Group

Addition of 4-methoxybenzyl alcohol to 3β-hydroxy-5α-androst-15-en-17-one gave the mixture of isomeric 15-(4-methoxyphenyl)methoxy derivatives from which, after acetylation and chromatography, the major 15β isomer was separated. Borohydride reduction gave 17β-hydroxy derivative which was protected as methoxymethyl ether. Oxidative cleavage of protecting group at position 15 and the subsequent Jones oxidation afforded corresponding 15-ketone. Its oximation with O-(carboxymethyl)hydroxylamine, deacetylation and methylation with diazomethane gave protected O-(carboxymethyl)oxime derivative with free hydroxy group at position 3. Its oxidation afforded dihydrotestosterone derivative and successive deprotection of position 17 and of carboxy group led to final (15E)-17β-hydroxy-5α-androstane-3,15-dione 15-[O-(carboxymethyl)]oxime. The title compound was designed as dihydrotestosterone hapten for heterologous radioimmunoassays.

Cleavage of the Epimines of 1,6-Anhydrohexoses with Fluoride Anion

2005 ◽  
Vol 70 (12) ◽  
pp. 2075-2085 ◽  
Author(s):  
Jiří Kroutil ◽  
Klára Jeništová
Keyword(s):  
Fluoride Anion ◽  
Ring Cleavage ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Aziridine Ring ◽  
Cleavage Reactions ◽  
Derivatives Of ◽  
Fluoro Derivatives

Aziridine ring cleavage reactions of five N-nosylepimines (2-6) having D-talo, D-galacto, D-manno, and D-allo configurations with potassium hydrogendifluoride under various reaction conditions have been performed. The cleavage regioselectively afforded diaxial isomers of vicinal amino-fluoro derivatives of 1,6-anhydro-β-D-gluco- and mannopyranose 7-11 in 51-94% yields. Removal of 2-nitrobenzenesulfonyl protecting group with benzenethiol has been attempted in the case of compound 10.

Spontaneous butenolide ring formation of pregnane-21-O-malonyl hemiesters under mild reaction conditions is facilitated by the 14β-hydroxy group present in all natural cardenolides

Tetrahedron ◽  
2016 ◽  
Vol 72 (30) ◽  
pp. 4556-4563 ◽  
Author(s):  
R.M. Pádua ◽  
N. Meitinger ◽  
M. Hennemann ◽  
P. Schebitz ◽  
R. Waibel ◽  
...  
Keyword(s):  
Hydroxy Group ◽  
Ring Formation ◽  
Reaction Conditions

Introduction of 4-Chlorophenyl: A Protecting Group for the Hydroxy Function

Synlett ◽  
2018 ◽  
Vol 29 (11) ◽  
pp. 1510-1516 ◽  
Author(s):  
Koichi Fukase ◽  
Yuji Otsuka ◽  
Toshihiro Yamamoto
Keyword(s):  
Hydroxy Group ◽  
Copper Catalyst ◽  
Pd Catalyst ◽  
Protecting Group ◽  
Acidic Conditions ◽  
Initial Conversion

4-Chlorophenyl ether was utilized as a new protecting group for the hydroxy function. This group was readily introduced to a sugar hydroxy group by using diaryliodonium triflate. Regioselective introduction of this protecting group at the vicinal cis-diol was achieved by using a copper catalyst and diaryliodonium triflate. This protecting group is stable under the Lewis acidic conditions of glycosylation, but it can be readily removed by the initial conversion into the corresponding 4-methoxyphenyl ether with use of a Pd catalyst, followed by oxidation with ammonium cerium (IV) nitrate [(NH4)2Ce(NO3)6] (CAN).

Bicyclization of aza-compounds by positive halide ions. I. Cyclic amines

1985 ◽  
Vol 63 (6) ◽  
pp. 1170-1172 ◽  
Author(s):  
R. M. Elofson ◽  
F. F. Gadallah ◽  
J. K. Laidler
Keyword(s):  
Electrochemical Oxidation ◽  
Halide Ions ◽  
Cyclic Amine ◽  
Reaction Conditions ◽  
Specific Reaction ◽  
Cyclic Amines ◽  
Bicyclic Compounds

Cyclic amines are oxidized to the bicyclic compounds by electrochemical oxidation. The presence of halide ions is found necessary for the reaction to proceed and to produce any bicyclic products. It is postulated that a positive halide species, X(+), is produced electrochemically and stabilized under the specific reaction conditions. The X(+) ion forms a complex with the parent cyclic amine which decomposes to the bicyclic product and HX. An analogy between the Hofer–Moest reaction to produce C(+) and this reaction to produce X(+) is postulated

Synthetic studies on tetrodotoxin and related compounds. V. The protecting group of the C9-hydroxy group

1974 ◽  
Vol 15 (4) ◽  
pp. 335-338 ◽  
Author(s):  
Hideo Tanino ◽  
Shoji Inoue ◽  
Matsuhiko Aratani ◽  
Yoshito Kishi
Keyword(s):  
Hydroxy Group ◽  
Protecting Group ◽  
Synthetic Studies ◽  
Related Compounds

Highly Enantioselective Michael Addition of Cyclic Diketones to β,γ-Unsaturated α-Keto Esters Catalyzed by Squaramide Organocatalyst

Synthesis ◽  
2022 ◽  
Author(s):  
Zhi-Wei Ma ◽  
Chuan-Chuan Wang ◽  
Quan-Jian Lv ◽  
Xiao-Pei Chen ◽  
Ai-Qin Li ◽  
...  
Keyword(s):  
Michael Addition ◽  
Large Scale ◽  
Catalyst System ◽  
Catalyst Loading ◽  
Reaction Conditions ◽  
Keto Esters ◽  
Bicyclic Compounds ◽  
Asymmetric Michael Addition ◽  
High Yields ◽  
Low Catalyst Loading

AbstractA new tertiary amine-squaramide organocatalyst has been developed and applied to the asymmetric Michael addition of cyclic diketones to β,γ-unsaturated α-keto esters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of synthetically and pharmaceutically useful chiral bicyclic compounds were obtained in high yields (up to 97%) with excellent enantioselectivities (up to 99 % ee). Furthermore, this catalytic system can be used efficiently in large-scale reactions with the yields and enantioselectivities being maintained.

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