Sequentielle Transformationen in der Organischen Chemie eine Synthesestrategie mit Zukunft

Abstract

Die organisch-chemische Synthese hat stets eine groIk Faszination auf den Chemiker ausgeiibt, und sie wird auch in Zukunft nichts von ihrer Bedeutung verlieren. Es ist eine Binsenweisheit, daR alle Chemiker ~ und nicht nur die ~ auf die Synthese chemischer Verbindungen, mit denen sie arbeiten wollen, angewiesen sind. So ist die organisch-chemische Synthese heute mehr denn je die Schnittstelle von Organischer Chemie, Biologie, Biochemie, Medizin, Physik und Materialwissenschaft. Man sollte auch nicht vergessen, daR die Grundlage der chemischen Industrie die Synthese ist. Fur den Synthetiker aus Leidenschaft aber ist die Synthese weit mehr als nur Mittel zu dem Zweck, Verbindungen in die Hand zu bekommen; sie ist Ausdruck seiner Kreativitat, Intelligeiiz und seines handwerklichen Konnens, aber auch seiner Ausdauer.

General and Efficient Organocatalytic Synthesis of Indoloquinolizidines, Pyridoquinazolines and Quinazolinones through a One‐Pot Domino Michael Addition‐Cyclization‐ Pictet–Spengler or 1,2‐Amine Addition Reaction

“…The crude reaction mixture was directly loaded for the column chromatography on silica gel to get the product 6a; yield: 42 mg (0.14 mmol, 68%). 4,6,7,12,12 b,13,3':3,4] 3826,3188,2963,2925,2867,1578,1524,1441,1359,1302,1251,1184,1109,1036,952,819,742 = 14.4,11.8,4.7,2.4 Hz,1 H),1 H),3.17 (ddd,J = 13.5,12.0,3.8 Hz,1 H),4.16 (dd,J = 13.6,3.4 37, 22.21, 22.29, 23.11, 27.38, 34.34, 35.87, 45.05, 50.12, 63.76, 107.99, 111.05, 111.42, 117.75, 119.17, 14] Adv. Synth.…”

“…Asymmetric cascade reactions have gained a lot of interest in recent years because of the notable advantages associated with them, including no need for time-consuming protection/deprotections steps or purification of the intermediates. [7,8] We have previously reported a general and practical enantioselective organocatalytic addition-cyclization cascade of 1,3-dicarbonyl compounds to a,b-unsaturated aldehydes. [9] In the presence of a catalytic amount of diarylprolinol ether as Lewis base, diketone 1 reacted with unsaturated aldehydes 2 to give chromenones 3.…”

Recent Developments in Asymmetric Organocatalytic Domino Reactions

“…Furthermore, no additional reagents, catalysts, or additives can be added to the reaction vessel, nor can reaction conditions be changed. [1] Denmark further posited, however, that most domino reactions, as defined by Tietze, fell under the broader category of tandem processes. [3] Other tandem reactions that are not cascades involve the isolation of intermediates, a change in reaction conditions, or the addition of reagents or coupling partners.…”

“…[ 1] It must be noted that there is a relatively narrow distinction between domino and consecutive cascade or tandem reactions. From the point of view of an operator, the only difference between the two lies in the point along the sequence at which one or more catalysts or reagents have to be added to effect either the initiation of a sequence (that is, domino reaction) or propagation to the next step (that is, consecutive reaction).…”

New thenoyl-substituted pyrrolo[1,2-c]quinazoline derivatives

“…These are all one-pot, multi-step sequences of reactions. 14 When the same mixture of quinazolinium salts 2 and 3 was heated in benzene, in the presence of an equimolecular amount of triethylamine, a new compound, 1-(2-thienoyl)-2-(2-thienyl)-pyrrolo[1,2-c]-quinazoline 8, was obtained (scheme 1 -route c).…”