Author: Andrew Peter Marcus
Publisher:
ISBN:
Category :
Languages : en
Pages : 584
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Book Description
En route to a total synthesis of tetrapetalone A, we have discovered an unexpected steric facilitation of the Nazarov cyclization of aryl dienyl ketones. Chapter 1 describes the success of the Nazarov cyclization of substrates possessing substituents at both the alpha- and gamma-positions of the acyclic dienone. Substrates possessing only one substituent at either the alpha- or gamma-position proceed much more slowly, or not at all. Density functional theory calculations on the Lewis acid-bound substrates and their respective transition states were performed by Rebecca Davis in the research group of Prof. Dean Tantillo at the University of California, Davis. The computations correlate closely with the observed reactivity. The effect is observed across a series of aryl dienyl ketones with an electron-rich arene portion. Further evidence for this effect was shown by the difficulty of effecting the Nazarov cyclization of a cyclic aryl dienone at room temperature. Chapter 2 describes the application of the findings of the Nazarov study to the synthesis of the indanone portion of tetrapetalone A. Difficulties in differentiation of the C-12 and C-14 positions (tetrapetalone numbering) of the indanone led to the investigation of a meta-bromo-containing aryl dienone, which successfully underwent the Nazarov cyclization with 13:1 regioselectivity. Formation of the C-N bond was achieved by performing a lithium-halogen exchange on the aryl bromide and quenching with tosyl azide, the product of which was then reduced to the free amine using lithium aluminum hydride. Chapter 3 describes the elaboration of the aniline intermediate to a late-stage tetracycle en route to tetrapetalone A. Closure of the tetracycle was achieved by Friedel-Crafts acylation onto a pyrrole in a double oxidation cascade. This sequence is promoted by Dess-Martin periodinane as both the oxidant and the activating agent for the carbonyl moiety. Installation of the angular ethyl group at C-4 was achieved by Birch reduction of the resulting 2-ketopyrrole followed by quenching with iodomethane. The correct substitution pattern on the tetramic acid was achieved following oxidation to the alpha, beta-unsaturated lactam and subsequent copper-mediated conjugate addition of bis(pinacolato)diboron, followed by further oxidation.
Author: Robert Gomer
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 216
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Book Description
Market: Students and researchers in vacuum and surface science, microscopy, and semiconductor physics. This definitive work was based on four lectures presented at Harvard University in 1958. When it was written, field emission was one of the few techniques available for surface studies and the attainment of ultra-high vacuum was a little-known art. Though more sophisticated treatments have since been developed, Gomer's pioneering work remains valid to this day.
Author: Teruaki Mukaiyama
Publisher: Oxford University Press, USA
ISBN:
Category : Chemistry, Organic
Languages : en
Pages : 248
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Book Description
This volume describes the life's work of Professor Teruaki Mukaiyama, one of Japan's most important and respected synthetic organic chemists. It includes information on his early research into a wide range of reactions, including dehydration reactions, the use of organosulfur compounds, and oxidation-reduction condensations in peptide and nucleotide synthesis reagents, as well as an account of Mukaiyama's important work on the applications of titanium compounds in organic synthesis. Three final chapters review Mukaiyama's work in synthetic control, stereoselective synthesis of carbohydrates, the stereoselective aldol, and Michael reactions. This unique book makes accessible much research that has only been available in Japanese, and provides a rare account of the contributions of one of the world's leading chemists.
Author: Lewis Rothberg
Publisher: World Scientific
ISBN: 9814493341
Category : Science
Languages : en
Pages : 245
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Book Description
Photoinduced charge transfer constitutes the scientific basis of photography, electrophotography and many biological processes. In addition, the science of charge photogeneration and transport in organic materials will be the basis of future generations of optoelectronic devices. This volume summarizes the state of the art in photoinduced charge transfer.
Author: Stephen R. Wilson
Publisher: John Wiley & Sons
ISBN: 9780471126874
Category : Medical
Languages : en
Pages : 288
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Book Description
The new time-saving revolution in drug discovery. Combinatorial chemistry, a method for synthesizing millions of chemical compounds much faster than usual, is becoming one of the most useful technical tools available to chemists and researchers working today. Using current advances in computer and laboratory techniques, combinatorial chemistry has freed professionals from the drudgery of piecemeal experimental work and opened new creative possibilities for experimentation. Combinatorial Chemistry: Synthesis and Application details critical aspects of the technique, featuring the work of some of the world's leading chemists, many of whom played a key role in its development. Including examples of both solution-phase and solid-phase approaches as well as the full complement of organic chemistry technologies currently available, the book describes: * Concepts and terms of combinatorial chemistry * Polymer-supported synthesis of organic compounds * Macro beads as microreactors * Solid-phase methods in combinatorial chemistry * Encoded combinatorial libraries, including Rf-encoding of synthesis beads * Strategies for combinatorial libraries of oligosaccharides * Combinatorial libraries of peptides, proteins, and antibodies using biological systems. While combinatorial chemistry originated in peptide chemistry, this volume has deliberately focused on nonpeptide organic applications, illustrating the technique's wide uses. Combinatorial Chemistry introduces organic, medicinal, and pharmaceutical chemists as well as biochemists to this exciting, cost-effective, and practical technique, which has unlocked creative potential for the next millennium.
