scholarly journals Synthesis of 1,5-bifunctional organolithium reagents by a double directed ortho-metalation: Direct transformation of esters into 1,8-dimethoxy-acridinium salts

Tetrahedron ◽  
2018 ◽  
Vol 74 (38) ◽  
pp. 5486-5493 ◽  
Author(s):  
Christian Fischer ◽  
Christof Sparr
Keyword(s):  
Direct Transformation ◽  
Organolithium Reagents ◽  
Ortho Metalation

Total Synthesis of (+)-Granatumine A and Related Bislactone Limonoid Alkaloids via a Pyran to Pyridine Interconversion

2019 ◽  
Author(s):  
Timothy Newhouse ◽  
Alexander Schuppe ◽  
Yizhou Zhao ◽  
Yannan Liu
Keyword(s):  
Total Synthesis ◽  
Inhibitory Activity ◽  
Knoevenagel Condensation ◽  
Cost Effective ◽  
Effective Procedure ◽  
Direct Transformation ◽  
Structural Revision ◽  
Alpha Beta ◽  
Ptp 1B

We report the first total synthesis of (+)-granatumine A, a limonoid alkaloid with PTP-1B inhibitory activity, in 10 steps. Over the course of this study, two key methodological advances were made: a cost effective procedure for ketone alpha,beta-dehydrogenation using allyl-Pd catalysis, and a Pd-catalyzed protocol to convert epoxyketones to 1,3-diketones. The central tetrasubstituted pyridine is formed by a convergent Knoevenagel condensation and carbonyl-selective electrocyclization cascade, which was followed by a direct transformation of a 2<i>H</i>-pyran to a pyridine. These studies have led to the structural revision of two members of this family.

Cyclization Dichotomy of D-xylo-Hex-5-ulosonamides and Synthesis of Piperidine Analogs of Aldohexoses and Aldohexono-1,5-lactones

1999 ◽  
Vol 64 (4) ◽  
pp. 673-684 ◽  
Author(s):  
Radka Kováříková ◽  
Miroslav Ledvina ◽  
David Šaman
Keyword(s):  
Boat Conformation ◽  
Direct Transformation

The preparation of 2,3,4,6-tetra-O-benzyl-5-D-xylo-hex-5-ulosonamides 3a and 3b and their cyclization to 5-amino-2,3,4,6-tetra-O-benzyl-5-deoxy-D-glucono-1,5-lactam (4) and 5-amino- 2,3,4,6-tetra-O-benzyl-5-deoxy-D-talono-1,5-lactam (5) or to 2,3,4,6-tetra-O-benzyl-1,5-dideoxy-1,5-imino-D-glucitol (9), and also their direct transformation into 2,3,4,6-tetra-O-benzyl- D-talono-1,5-lactone (6), are described and discussed. The atypical boat conformation of D-talonolactam 5 and D-talonolactone 6 was found.

Transition-metal-free and facile synthesis of 3-alkynylpyrrole-2, 4-dicarboxylates from methylene isocyanides and propiolaldehyde

2021 ◽  
Author(s):  
Xiaoli Huo ◽  
Xiaojuan Chen ◽  
Liya Yu ◽  
Chong Zhang ◽  
Linghui Zeng ◽  
...  
Keyword(s):  
Transition Metal ◽  
Efficient Method ◽  
Transformation Process ◽  
Facile Synthesis ◽  
Direct Transformation ◽  
Metal Free

A transition-metal-free, facile and efficient method for the synthesis of 3-alkynylpyrrole-2, 4-dicarboxylates from methylene isocyanides and propiolaldehyde with moderate to good yields has been developed. The direct transformation process and...

Synthesis of unsymmetrical phenylurea derivatives via oxidative cross coupling of aryl formamides with amines under metal-free conditions

2015 ◽  
Vol 39 (2) ◽  
pp. 805-809 ◽  
Author(s):  
Nagireddy Veera Reddy ◽  
Pailla Santhosh Kumar ◽  
Peddi Sudhir Reddy ◽  
Mannepalli Lakshmi Kantam ◽  
Kallu Rajender Reddy
Keyword(s):  
Cross Coupling ◽  
Hypervalent Iodine ◽  
Direct Transformation ◽  
Metal Free

A direct transformation of N-aryl formamides to the corresponding phenylurea derivatives via the formation of isocyanate intermediates is achieved in good yields using hypervalent iodine reagents as external oxidants.

Reactivity of α,β-unsaturated acetals and ketals toward organolithium reagents in pentane

1984 ◽  
Vol 25 (5) ◽  
pp. 519-522 ◽  
Author(s):  
Charles Mioskowski ◽  
S. Manna ◽  
J.R. Falck
Keyword(s):  
Organolithium Reagents

Direct Synthesis of 3,5-Dinitropyrazole Catalyzed by Newly Sulfated Nanosolid Superacid TiO2/ SO

2011 ◽  
Vol 391-392 ◽  
pp. 1296-1301
Author(s):  
Li Min Xi ◽  
Xin Xin Zhang
Keyword(s):  
Direct Synthesis ◽  
Sol Gel ◽  
Acid Base ◽  
Direct Transformation ◽  
Acid Base Titration ◽  
Optimal Reaction Condition ◽  
Superacid Catalyst ◽  
Average Size ◽  
Optimal Reaction ◽  
Xrd And Tem

The newly sulfated nanosolid superacid TiO2/SO4 prepared by sol-gel method was broadly characterized by acid base titration, XRD and TEM, which identified that the superfine solid TiO2/SO4 showing good dispersibility with average size of 27 nm belongs to kind of crystalline nanoparticles. With the help of the catalyst TiO2/SO4, the optimal reaction condition for direct transformation of pyrazole and nitrosonitric acid into 3, 5-Dinitropyrazole was n (pyrazol)=0.10 mol, m (TiO2/SO4 )＝1.5g, V(n-octannol)＝90mL, and V(nitrosonitric acid)＝50mL. Moreover, the optimal yield of the catalytic reaction reached up to 59.4% when the reaction time is 7 hours. The nanosolid superacid catalyst is still of high activity after regenerating eight times by calcination at 600。C.

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