Stereocontrolled synthesis of rosuvastatin calcium via iodine chloride-induced intramolecular cyclization

2016 ◽  
Vol 14 (4) ◽  
pp. 1363-1369 ◽  
Author(s):  
Fangjun Xiong ◽  
Haifeng Wang ◽  
Lingjie Yan ◽  
Sheng Han ◽  
Yuan Tao ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Stereocontrolled Synthesis ◽  
Iodine Chloride ◽  
Rosuvastatin Calcium

A novel, stereoselective approach towards rosuvastatin calcium from the known (S)-homoallylic alcohol has been developed.

The Unsaturation of Butadiene Rubbers. I

1949 ◽  
Vol 22 (2) ◽  
pp. 287-298
Author(s):  
A. A. Vasil'ev
Keyword(s):  
Intramolecular Cyclization ◽  
Degree Of Saturation ◽  
Double Bonds ◽  
Iodine Chloride ◽  
Iodine Bromide

Abstract 1. The data on the unsaturation of butadiene rubbers previously obtained by using the method based on the reaction with iodine bromide have been checked and confirmed with the aid of the reactions with pyridine sulfate dibromide and with iodine chloride. 2. The influence of various factors on the unsaturation of butadiene rubbers has been checked, and the possibility of estimating changes in unsaturation with the aid of the reaction with iodine bromide has been established. 3. The present investigation shows that, during the reaction between butadiene rubbers and halogens, it is impossible to attain a degree of saturation exceeding 85–90 per cent of the theoretical values. This is apparently due to the existence of intramolecular cyclization, to the presence of intermolecular connecting bridges, and possibly to the presence of double bonds resistant to halogenation or of conjugated double bonds in the molecules of these rubbers. The reaction with halogens offers no possibility of confirming these suppositions experimentally.

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>

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

Stereocontrolled synthesis of tetrahydrofurans and tetrahydropyrans using thallium(III)-induced cyclizations

1985 ◽  
Vol 50 (14) ◽  
pp. 2416-2423 ◽  
Author(s):  
Joseph P. Michael ◽  
Pauline C. Ting ◽  
Paul A. Bartlett
Keyword(s):  
Stereocontrolled Synthesis
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