Metalation of diazines.XI. Directedortho-lithiation of fluoropyrimidines and application to synthesis of an azacarboline

Regioselective Fluorination of 1-(2,2-Dibromovinyl)benzene Derivatives with Wet Tetra-n-butylammonium Fluoride: One-Pot Synthesis of (Z)-1-(2-Bromo-1-fluorovinyl)benzenes

A direct fluorination of 1-(2,2-dibromovinyl)benzene derivatives using wet tetra-n-butylammonium fluoride (TBAF·3H2O) as either a base or a fluorine source in toluene was accomplished, which provided (Z)-1-(2-bromo-1-fluorovinyl)benzene compounds in up to 81% yields with high regioselectivities. This reaction results strongly depend upon the reaction conditions. The mechanism of this reaction was investigated as well.

Synthesis of pyrido[2,3-b]indoles and pyrimidoindoles via Pd-catalyzed amidation and cyclization

Biologically and pharmaceutically active core structures containing a new class of 4-hydroxy-α-carbolines, dihydropyrido[2,3-b]indoles, pyrimido[4,5-b] and [5,4-b]indoles have been synthesized in good yields via Pd-catalyzed amidation and cyclizations. The keto-enol tautomerism in 4-hydroxy-α-carbolines has been investigated by DFT calculations and spectroscopic techniques. The fluorescence studies of pyrimido[4,5-b] and [5,4-b]indoles were carried out with good quantum yields.

Selective Synthesis of Functionalized Thia- and Oxacalix[2]arene[2]pyrimidines

Functionalized oxacalix[m]arene[n]pyrimidines have been synthesized by S(N)Ar on 4,6-dihalopyrimidine building blocks. Depending on the S(N)Ar conditions, either a mixture of oxacalix[n]arenes, ranging from oxacalix[4]- up to oxacalix[12]arene, could be prepared or the oxacalix[4]arene could be synthesized selectively in a high yield. The electrophilic (pyrimidine) and the nucleophilic components could both be varied, allowing the preparation of functionalized oxacalix[4]arenes. Moreover, the procedure also gives access to the analogous thiacalix[4]arenes.

Lithiation of 3-(Acylamino)-2-unsubstituted-, 3-(Acylamino)-2-ethyl-, and 3-(Acylamino)-2-propyl-4(3H)-quinazolinones: Convenient Syntheses of More Complex Quinazolinones(1)

3-(Pivaloylamino)- and 3-(acetylamino)-4(3H)-quinazolinones react with alkyllithium reagents to give 1,2-addition products in very good yields. Lithiation takes place with LDA and is regioselective at position 2. The lithium reagents thus obtained react with a variety of electrophiles to give the corresponding substituted derivatives in very good yields. Reactions of the lithium reagents with iodine give oxidatively dimerized cyclic structures. 3-(Pivaloylamino)- and 3-(acetylamino)-2-ethyl-4(3H)-quinazolinones and 3-(pivaloylamino)- and 3-(acetylamino)-2-propyl-4(3H)-quinazolinones are lithiated at the benzylic position with LDA. The lithium reagents so produced also react with a variety of electrophiles to give the corresponding 2-substituted-4(3H)-quinazolinone derivatives in very good yields. However, lithiation of 3-(acylamino)-2-(1-methylethyl)-4(3H)-quinazolinones was unsuccessful, as were lithiations of compounds having a diacetylamino group at position 3. The amide groups have been cleaved in good yield under basic or acidic conditions from some of the products to provide access to the free amino compounds.