scholarly journals Acid-catalyzed and photolytic reactivity of some unsaturated B-nor-5, 10-secosteroidal ketones

2003 ◽  
Vol 68 (4-5) ◽  
pp. 303-312 ◽  
Author(s):  
Mira Bjelakovic ◽  
Vladimir Pavlovic ◽  
Milan Dabovic ◽  
Ljubinka Lorenc
Keyword(s):  
Uv Irradiation ◽  
Intramolecular Cyclization ◽  
Unsaturated Compound ◽  
Acid Catalyzed

The acid-catalyzed reaction of (Z)- and (E)-B-nor-5,10-seco-ketones 2 and 3 resulted in an intramolecular cyclization to give the 5-hydroxy-A-nor-1?,5?-10(19)-methylidene derivative 8, the 5?-hydroxy-A-nor-1(10)-unsaturated compound 9 and the 5?,10?-dihydroxy A-nor-product 10, from the (Z)-isomer and the 5-hydroxy-A-nor-1?,5?-10(19)-methylidene product 11, from the (E)-isomer. Upon UV-irradiation, the (Z)- and (E)-seco-ketones 2 and 3 underwent a reversible (Z)/(E) and (E)/(Z)-isomerization and in addition to a transannular photocyclization to afford the 10(19)-methylidene derivatives 8 and 11, respectively, while photolysis of the 10(19)-methylidene-B-nor-5,10-seco-ketone 4 gave the oxetane derivative 12.

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.

Intramolecular cyclization of N-phenylanthranilic acid catalyzed by MCM-41 with different pore diameters

2015 ◽  
Vol 41 (12) ◽  
pp. 10125-10135 ◽  
Author(s):  
Shangyou Xiao ◽  
Guang Xu ◽  
Gang Chen ◽  
Xiaojing Mu ◽  
Zhitao Chen ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Acid Catalyzed ◽  
Mcm 41

4-β-D-Ribofuranosyl-1,2,4-triazin-3,5(2H,4H)-dione and 4-β-D-ribofuranosyl-6-methyl-1,2,4-triazin-3,5(2H, 4H)-dione

1982 ◽  
Vol 47 (3) ◽  
pp. 994-999 ◽  
Author(s):  
Hubert Hřebabecký
Keyword(s):  
Uv Irradiation ◽  
Sodium Methoxide ◽  
Methanolic Solution ◽  
Acid Catalyzed ◽  
Methyl Pyruvate

4-β-D-Ribofuranosyl-1,2,4-triazin-3,5(2H,4H)-dione (IX) and 4-β-D-ribofuranosyl-6-methyl-1,2,4,-triazin-3,5(2H,4H)-dione (XI) were prepared by cyclization of (Z)-4-β-D-ribofuranosyl-semicarbazones of methyl glyoxylate (VI) and methyl pyruvate (VIII) in the methanolic solution of sodium methoxide. A mixture of (E)- and (Z)-ribosylsemicarbazones III and IV was prepared by condensation of the ribosylsemicarbazide I with methyl dimethoxyacetate and a mixture of (E)-and (Z)-isomers V and VIII was obtained on condensation of I with methyl pyruvate. The (Z) isomer VI was prepared on acid-catalyzed isomerisation of the (E)-isomer III while the (Z)-isomer VIII was obtained on the UV-irradiation of isomer V.

scholarly journals Acid-Catalyzed Hydrolysis and Intramolecular Cyclization of N-Cyano Sulfoximines for the Synthesis of Thiadiazine 1-Oxides

ACS Omega ◽  
2022 ◽  
Author(s):  
In Seok Oh ◽  
Ye Ji Seo ◽  
Ji Young Hyun ◽  
Hwan Jung Lim ◽  
Duck-Hyung Lee ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Acid Catalyzed

Acid-catalyzed intramolecular cyclization of N-(4,4-diethoxybutyl)sulfonamides as a novel approach to the 1-sulfonyl-2-arylpyrrolidines

2016 ◽  
Vol 47 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Almir S. Gazizov ◽  
Andrey V. Smolobochkin ◽  
Ekaterina A. Anikina ◽  
Julia K. Voronina ◽  
Alexander R. Burilov ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Novel Approach ◽  
Acid Catalyzed

Brønsted acid-catalyzed synthesis of carbazoles from 2-substituted indoles

2014 ◽  
Vol 1 (10) ◽  
pp. 1197-1200 ◽  
Author(s):  
Qingjiang Li ◽  
Xiao-Shui Peng ◽  
Henry N. C. Wong
Keyword(s):  
Intramolecular Cyclization ◽  
Sonogashira Coupling ◽  
Terminal Alkynes ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Efficient Approach ◽  
Brönsted Acid ◽  
Acid Catalyzed

A simple and efficient approach for the synthesis of disubstituted carbazoles has been developed from o-haloanilines and terminal alkynes using a two-step strategy, namely, Sonogashira coupling and intramolecular cyclization.

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