Model studies of thiamine catalysis. Comparison of the effects of heteroatoms at annular positions on side-chain kinetic acidity

1978 ◽  
Vol 43 (9) ◽  
pp. 1713-1718 ◽  
Author(s):  
John A. Zoltewicz ◽  
John K. O'Halloran
Keyword(s):  
Side Chain ◽  
Model Studies ◽  
Kinetic Acidity

Experiments directed towards the synthesis of anthracyclinones. VII. Model studies with allyl naphthalenyl ethers

1983 ◽  
Vol 36 (4) ◽  
pp. 803 ◽  
Author(s):  
IK Boddy ◽  
RC Cambie ◽  
G Dixon ◽  
PS Rutledge ◽  
PD Woodgate
Keyword(s):  
Claisen Rearrangement ◽  
Side Chain ◽  
Model Studies ◽  
Chain Isomerization

The Claisen rearrangement of some allyl naphthalen-1-yl ethers has been examined, together with methods for modification of the resulting 2-ally1 side chain. Isomerization of the C-allyl substituent to a prop-1-enyl group followed by ozonolysis gives a formyl derivative, while ozonolysis of a 2-(2-methylprop-2-enyl) moiety or mercuriation of a 2-(2-chloroprop-2-enyl) substituent leads to an acetonyl derivative. Treatment of phenols with iodine(I) acetate and an excess of silver(I) acetate gives 4-hydroxyaryl acetates, probably via dienone intermediates.

Model Studies on Protein Side Chain Modification by 4-Oxo-2-nonenal†

2003 ◽  
Vol 16 (4) ◽  
pp. 512-523 ◽  
Author(s):  
Wei-Han Zhang ◽  
Jiyun Liu ◽  
Guozhang Xu ◽  
Quan Yuan ◽  
Lawrence M. Sayre
Keyword(s):  
Side Chain ◽  
Model Studies

scholarly journals Evolution of a Cycloaddition–Rearrangement Approach to the Squalestatins: A Quarter-Century Odyssey

Synlett ◽  
2020 ◽  
Vol 31 (16) ◽  
pp. 1555-1572
Author(s):  
David M. Hodgson ◽  
Hasanain A. A. Almohseni
Keyword(s):  
Second Generation ◽  
Alternative Strategy ◽  
Side Chain ◽  
Quarter Century ◽  
Oxidation Level ◽  
Asymmetric Model ◽  
Subsequent Oxidation ◽  
Model Studies ◽  
Zaragozic Acids ◽  
Carbonyl Ylide

The highs, lows, and diversions of a journey leading to two syntheses of 6,7-dideoxysqualestatin H5 is described. Both syntheses relied on highly diastereoselective n-alkylations of a tartrate acetonide enolate and subsequent oxidation–hydrolysis to provide an asymmetric entry to β-hydroxy-α-ketoester motifs. The latter were differentially elaborated to diazoketones which underwent stereo- and regioselective Rh(II)-catalysed cyclic carbonyl ylide formation–cycloaddition and then acid-catalysed transketalisation to generate the 2,8-dioxabicyclo[3.2.1]octane core of the squalestatins/zaragozic acids at the correct tricarboxylate oxidation level. The unsaturated side chain was either protected with a bromide substituent during the transketalisation or introduced afterwards by a stereoretentive Ni-catalyzed Csp3–Csp2 cross-electrophile coupling.1 Introduction  2 Racemic Model Studies to the Squalestatin/Zaragozic Acid Core3 Asymmetric Model Studies to a Keto α-Diazoester3.1 Dialkyl Squarate Desymmetrisation3.2 Tartrate Alkylation3.2.1 Further Studies on Seebach’s Alkylation Chemistry 4 Failure at the Penultimate Step to DDSQ 5 Second-Generation Approach to DDSQ: A Bromide Substituent Strategy 5.1 Stereoselective Routes to E-Alkenyl Halides via β-Oxido Phosphonium Ylides 5.2 Back to DDSQ Synthesis6 An Alternative Strategy to DDSQ: By Cross-Electrophile Coupling7 Alkene Ozonolysis in the Presence of Diazo Functionality: Accessing α-Ketoester Intermediates8 Summary

Remote halogenation: Some model studies and specific degradation of the cholesterol, sitosterol, and campesterol side chain

Tetrahedron ◽  
1985 ◽  
Vol 41 (20) ◽  
pp. 4509-4517 ◽  
Author(s):  
Peter Welzel ◽  
Kurt Hobert ◽  
Aranka Ponty ◽  
Dirk Neunert ◽  
Harald Klein ◽  
...  
Keyword(s):  
Side Chain ◽  
Model Studies ◽  
Specific Degradation
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