Application of Matrix-assisted Laser Desorption/ Ionization Time-of-flight Mass Spectrometry to the Structure Determination of Medium and Large Macrocycles Formed by Palladium(0)- catalyzed Allylation of Arenesulfonamides, Sulfamide, and Cyanamide Sı ´lvia Cerezo 1 , Jordi Corte ´s 1 , David Galvan 1 , Juan-Manuel Lo ´pez-Romero 1 , Marcial Moreno- Man ˜as 1 , Roser Pleixats 1 , Francesc X. Avile ´s 2 , Francesc Canals 2 and Anna Roglans 3 * 1 Department of Chemistry, Universitat Auto `noma de Barcelona, Bellaterra, 08193-Barcelona, Spain 2 Institut de Biologia Fonamental, Universitat Auto `noma de Barcelona, Bellaterra, 08193-Barcelona, Spain 3 Department of Chemistry, Universitat de Girona, Campus de Montilivi, 17071-Girona, Spain Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry allowed the direct determina- tion of the extent of macrocyclic and linear oligomer formation in the palladium(0)-catalyzed allylation of highly acidic and non-nucleophilic arenesulfonamides, sulfamide, and cyanamide. Palladium-containing 15- membered-ring macrocyclic compounds gave unusual [M  H]  ions besides [M  Na]  and [M  K]  adducts. Copyright # 1999 John Wiley & Sons, Ltd. Received 27 May 1999; Revised 16 September 1999; Accepted 6 October 1999 Matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that allows macromolecules to be efficiently ionized and vaporized without degradation. 1 This analytical technique has been widely used for the direct determination of molecular weight of biopolymers, 2–5 synthetic polymers, 6,7 macrocyclic oligomers, 8–14 and also low molecular weight compounds. 15 Some of us have recently reported 16 that arenesulfona- mides, cyanamide, and sulfamide react with allylic bis- carbonates under palladium(0) catalysis to afford medium and large unsaturated macrocycles. Structural elucidation of these macrocyclic compounds by non-mass-spectrometric methods was not trivial since some of them presented similar IR and 1 H-NMR spectra. Herein, we want to demonstrate that MALDI time-of-flight mass spectrometry (MALDI-TOF-MS) is the best method for the analysis of the molecular composition of the mixtures produced during the allylation process. EXPERIMENTAL Samples and materials Preparation of most of the compounds under analysis is described in detail in a previous paper. 16 Compounds 6d and 7d (refer to Table 2) were prepared by reaction of 2- nitrobenzenesulfonamide and 3-chloro-2-(chloromethyl)-1- propene following a general described 17 methodology. The compounds under investigation are summarized in Schemes 1 and 2 and Tables 1 and 2. Organic solvents (tetrahydrofuran (THF) and CHCl 3 ) were analytical grade. The matrices, a-cyano-4-hydroxy- cinnamic acid (CCA) and 2,5-dihydroxybenzoic acid (DHB) were both purchased from Aldrich Chemical Co. (Milwankee, WI, USA). Sinapinic acid was purchased from Fluka Chemie AG-(Buchs, Switzerland). All matrices were used without further purification. Mass spectrometry MALDI-TOF mass spectra were performed on a BIFLEX spectrometer (Bruker-Franzen Analytik, Bremen, Germany) equipped with a pulsed nitrogen laser (337 nm), operating in positive-ion reflector mode, and using a 19 kV acceleration voltage. Matrices were prepared at 5 mg/mL in THF. Analytes were dissolved at concentrations between 0.1 and 5 mg/mL in CHCl 3 . Samples were prepared by mixing equal volumes of the analyte and matrix solutions. From this mixture, 1mL was spotted on a stainless steel sample holder and allowed to evaporate to dryness at room temperature. Mass spectra were obtained by averaging the signals from 20–100 laser shots at 2–10 different spots within the sample. Ions with m/z below 200–400 (depending on the sample analyzed) were deflected to avoid detector saturation. Calibration was performed using standard peptides (ob- tained from Sigma). Mass accuracy was typically below 50 ppm (internal calibration) or 0.05% (external calibra- tion). RESULTS AND DISCUSSION Since the macrocyclic structures 1 and 2 (see Scheme 1 and Table 1) presented similar IR and 1 H/ 13 C-NMR spectra and *Correspondence to: A. Roglans, Department of Chemistry, Uni- versitat de Girona, Campus de Montilivi, 17071 Girona, Spain. Contract/grant sponsor: DGICYT; Contract/grant number: PB93-0896 and BIO98-0362. Contract/grant sponsor: CIRIT; Contract/grant number: 98SGR0056. Contract/grant sponsor: Centre de Refere `ncia de Biotecnologia. CCC 0951–4198/99/232359–07 $17.50 Copyright # 1999 John Wiley & Sons, Ltd. RAPID COMMUNICATIONS IN MASS SPECTROMETRY Rapid Commun. Mass Spectrom. 13, 2359–2365 (1999)