Synthesis of some partially methylated sucrose derivatives

1972 ◽  
Vol 25 (2) ◽  
pp. 407 ◽  
Author(s):  
GW O'Donnell ◽  
GN Richards
Keyword(s):  
Boron Trifluoride ◽  
Liquid Ammonia ◽  
Major Product ◽  
Methyl Derivative ◽  
Hydrolysis Products ◽  
Subsequent Deacetylation ◽  
Partially Methylated

1',6,6'-Tri-O-methylsucrose, a new compound, has been synthesized by methylation of 2,3,3',4,4'-penta-O-acetylsucrose with diazomethane and boron trifluoride with subsequent deacetylation. 2,3,3',4,4'-Penta-O-methylsucrose has been obtained in improved yield from the tri-O-trityl derivative by reduction with lithium in liquid ammonia. A major product of the incomplete methylation of 11,6,6'-tri-O-tritylsucrose was the 2,3,3',4'-tetra-O-methyl derivative, and after reductive detritylation 2,3,3',4'-tetra-O-methylsucrose, a new compound, was isolated and identified by examination of its hydrolysis products.

Tetracyclic triterpenes. VIII. The skeletal rearrangement of 3β-acetoxy-9α,11α-epoxy-5α-lanostan-7-one: 13- and 10-methyl group migration

1985 ◽  
Vol 63 (6) ◽  
pp. 1280-1286 ◽  
Author(s):  
Zdzisław Paryzek ◽  
Roman Wydra
Keyword(s):  
Acetic Anhydride ◽  
Spectral Data ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Major Product ◽  
Chemical Transformations ◽  
Skeletal Rearrangement ◽  
Methyl Group ◽  
Group Migration

The boron trifluoride etherate catalyzed rearrangement of 3β-acetoxy-9α, 11α-epoxy-5α-lanostan-7-one (1) in acetic anhydride resulted in formation of 19(10 → 9β)abeo compounds 2 and 4 along with 18(13 → 12β)abeo compound 5, as the major product. These structures are supported by spectral data and chemical transformations. The possible mechanism of the rearrangement is discussed.

Preparation of Some 9-Hydroxy-2-oxaspiro[4.5]dec-8-ene-1,7-dione Derivatives by Reductive Alkylation of 3,5-Dimethoxybenzoic Acid With 1,2-Dihaloalkane and Oxiran Electrophiles

1989 ◽  
Vol 42 (8) ◽  
pp. 1207 ◽  
Author(s):  
JS Wilkie ◽  
KN Winzenberg
Keyword(s):  
Carboxylic Acid ◽  
Acid Hydrolysis ◽  
Liquid Ammonia ◽  
Major Product ◽  
Reductive Alkylation

Lithium in liquid ammonia mediated reductive alkylation of 3,5-dimethoxybenzoic acid (3) with 1,2-dibromoethane, or 1-bromo-2-chloroethane, followed by acid hydrolysis, afforded 9-hydroxy-2-oxaspiro[4.5]dec-8-ene-1,7-dione (1a). Reductive alkylation of (3) with unbranched 1,2-dibromoaikanes (5b-g), 1,2-dibromo-3-methylbutane and 1,2-dibromo-3,3-dimethylbutane gave 3-alkyl-9-hydroxy-2-oxaspiro[4.5]dec-8-ene-1,7-dione derivatives (1b-i) in moderate yields with the exception of (1i). The major product of the last reaction was 1-(2-bromo-3,3- dimethylbutyl )-3-hydroxy-5-oxocyclohex-3-ene-1-carboxylic acid (9). No reductive alkylation of (3) was observed with 2,3-dibromobutane or 1,2-dibromo-2methylpropane. Reductive alkylation of (3) with the oxiran derivatives (8a-d) afforded the 2-oxaspiro[4.5]dec-8-ene-1,7- dione derivatives (1a-c,j). Reductive alkylation of (3) with 1,3-dibromopropane and l-bromo-3-chloropropane gave, after hydrolysis, 1-(3-bromopropyl)-3-hydroxy-5-oxocyclohex-3-ene-l- carboxylic acid (12a) and 1-(3-chloropropyl)-3-hydroxy-5-oxocyclohex-3-ene-1-carboxylic acid (12b). The conversion of (1a) into 8-[1-( ethoxyimino )butyl]-9-hydroxy-2-oxaspiro[4.5]dec-8-ene-1,7-dione (2a) is described.

Synthesis of methyl 3,4-di-O-(β-D-xylopyranosyl)-β-D-xylopyranoside, a methyl β-xylotrioside related to branched xylans

1979 ◽  
Vol 44 (3) ◽  
pp. 928-932 ◽  
Author(s):  
Pavol Kováč
Keyword(s):  
Methyl Derivative ◽  
Subsequent Deacetylation

The condensation of 2,3,4-tri-O-acetyl-α-D-xylopyranosyl bromide (I) with methyl 2-O-benzyl-β-D-xylopyranoside (II) afforded methyl 2-O-benzyl-3,4-di-O-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl)-β-D-xylopyranoside (III). Hydrogenolytic cleavage of the benzyl group from III and subsequent deacetylation led to the crystalline title methyl β-xylotrioside (V) related to branched xylans. Compound V was characterized by its crystalline per-O-acetate VI and per-O-methyl derivative VII.

Stereoselectivity of C(3)-methylation of camphor and derivatives

1984 ◽  
Vol 62 (10) ◽  
pp. 1899-1902 ◽  
Author(s):  
John H. Hutchinson ◽  
Thomas Money
Keyword(s):  
Major Product ◽  
Methyl Derivative

Contrary to general expectations, kinetic methylation of camphor, 9-bromocamphor, or 9,10-dibromocamphor produces the 3-exo-methyl derivative as the major product.

Recent advances in the chemistry of uranium halides in anhydrous ammonia

2018 ◽  
Vol 233 (12) ◽  
pp. 817-844 ◽  
Author(s):  
Stefan S. Rudel ◽  
Sebastian A. Baer ◽  
Patrick Woidy ◽  
Thomas G. Müller ◽  
H.-Lars Deubner ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Liquid Ammonia ◽  
Ammine Complexes ◽  
Anhydrous Ammonia ◽  
Hydrolysis Products ◽  
Recent Advances

Abstract This article presents an overview of recent advancements in the field of uranium chemistry, paying special attention to the preparation of starting materials and to the chemistry of uranium halides in liquid ammonia. Where suitable, insights into the chemistry of thorium are also presented. Herein, we report upon the crystal structures of several ammine complexes as well as their deprotonation products. Specific examples of hydrolysis products in liquid ammonia are showcased. Additionally, advancements in the preparation of uranium cyanides are presented.

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