Regioselective quinazoline C2 modifications through the azide-tetrazole tautomeric equilibrium.

2-Chloro-4-sulfonylquinazolines undergo functional group swap when treated with an azide nucleophile: 1) the azide replaces the sulfonyl group at the C4 position; 2) the intrinsic azide-tetrazole tautomeric equilibrium directs the nucleofugal sulfinate from the first step to replace chloride at the C2 position. This transformation is effective with quinazolines bearing electron-rich substituents. Therefore, the title transformations are demonstrated on the 6,7-dimethoxyquinazoline core, which is present in pharmaceutically active substances.

Never-Ending Story: New Cyclodextrin-Based Metal-Organic Framework Crystal Structures Obtained Using Different Crystallization Methods.

Six novel cyclodextrin (CD)-based metal-organic frameworks (MOFs) were synthesized using distinct crystallization methodologies. A modified vapor diffusion method is introduced for the first time, termed fast crystallization, which enables the rapid solid-state formation of MOF compounds. This innovative method yielded four of the newly synthesized MOFs.

1,2-Silyl Shift-Induced Heterocyclization of Propargyl Silanes: Synthesis of Five-Membered Heterocycles Containing a Functionalized Olefin Side Chain.

Propargyl silanes with a terminal alkyne moiety undergo a 1,2-silyl shift when activated with electrophiles such as H, Br, I, and PhSe. A method was developed to trap 1,3-transposed electrophilic centers with various internal O-, N-, and S-nucleophiles in a 5-exo manner. This synthetic procedure provided five-membered heterocycles containing a trisubstituted olefin side chain.

1,3-Difunctionalization of Propargyl Silanes with Concomitant 1,2-Silyl Shift: Synthesis of Allyl Functionalized Vinyl Silanes.

Terminal alkynes with a silyl group at the propargylic position upon activation with electrophiles such as -bromosuccinimide undergo ()-selective 1,2-silyl group migration. Subsequently, an allyl cation is formed that is intercepted by an external nucleophile. This approach provides allyl ethers and esters with stereochemically defined vinyl halide and silane handles for further functionalization.

SnAr Reactions of 2,4-Diazidopyrido[3,2-]pyrimidine and Azide-Tetrazole Equilibrium Studies of the Obtained 5-Substituted Tetrazolo[1,5-]pyrido[2,3-]pyrimidines.

A straightforward method for the synthesis of 5-substituted tetrazolo[1,5-]pyrido[2,3-]pyrimidines from 2,4-diazidopyrido[3,2-]pyrimidine in SnAr reactions with -, -, and - nucleophiles has been developed. The various - and -substituted products were obtained with yields from 47% to 98%, but the substitution with -nucleophiles gave lower yields (20-32%). Furthermore, the fused tetrazolo[1,5-]pyrimidine derivatives can be regarded as 2-azidopyrimidines and functionalized in copper(I)-catalyzed azide-alkyne dipolar cycloaddition (CuAAC) and Staudinger reactions due to the presence of a sufficient concentration of the reactive azide tautomer in solution.