We have previously reported that the palladium-catalyzed cross-coupling reaction of air-stable potassium alkenyltrifluoroborates with aryl halides and triflates proceeds readily with good yields. Recent progress in outlining the scope and limitations of such reactions is described herein. The palladium-catalyzed cross-coupling reaction of potassium alkenyltrifluoroborates with aryl and heteroaryl halides and triflates proceeds readily with moderate to excellent yields. The alkenyl cross-coupling reaction can generally be effected using 2 mol % of PdCl2(dppf).CH2Cl2 as catalyst in i-PrOH-H2O in the presence of t-BuNH2 as the base. A variety of functional groups are tolerated in both partners, and the process is stereospecific with regard to the alkenyltrifluoroborate starting material.

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In a solvent-free system, the microwave irradiation of mixtures of N-sulfonyl tetrahydroisoquinolines and 37% potassium fluoride supported on alumina selectively furnished 3,4-dihydroisoquinolines or isoquinolines, depending upon the reaction time.Chemical transformations carried out with supported reagents under dry conditions have several significant advantages over reactions traditionally run in solution; they offer easier separation of the products, new or better selectivities, faster processes or milder reaction conditions, less waste problems and the possibility of working in a continuous way. 1 Potassium fluoride on alumina (KF/Al 2 O 3 ) has been reported as a solid supported reagent for alkylation, 2 elimination, 3 addition, 4 condensation, 5 enolization, desilylation, 6 coupling 7 and other useful reactions. It has been shown that during the impregnation-activation procedure, the salt reacts with aluminium oxide forming K 3 AlF 6 and an active mixture of KOH and potassium aluminate on the surface of the solid support, 8 which would contribute to explain its reactivity.On the other hand, the enhancement of chemical transformations by microwave irradiation of organic molecules supported on inorganic solids has experienced an enormous growth in recent years, 9 as this technique is manipulatively simple, can be conducted rapidly and provides products in high yields employing solvent-free conditions.Recent work informed that under microwave assistance KF/Al 2 O 3 cleaves sulfonamides to the corresponding amines in dry conditions. 10 However, the irradiation of mixtures of N-sulfonyl isoquinoline derivatives and KF/ Al 2 O 3 has not been studied to date.N-sulfonyl-type protecting groups are widely used in isoquinoline chemistry, specially in the N-activated PictetSpengler synthesis 11,12 and in many variations of the Pomerantz-Fritsch sequence. 13 Removal of the sulfonyl moiety by taking advantage of the different oxidation states of sulfur has been employed to broaden the scope of these synthetic protocols, but only a few methods have been described. 11,13 Herein, we wish to report the selective elaboration of 3,4-dihydroisoquinolines and isoquinolines (Scheme 1) by the microwave-assisted oxidative desulfonylation and subsequent dehydrogenation (for isoquinolines) of N-sulfonyl tetrahydroisoquinolines with KF/Al 2 O 3 as solid supported reagent, in non-solvent conditions. Scheme 1 Reagents and Conditions: a) 37% KF/Al 2 O 3 , Microwaves (time: t 1 < t 2 ). Table 1 were prepared employing a modified activated PictetSpengler procedure, by reaction of a-phenylchalcogen-ahalocarbonyls as aldehyde surrogates with conveniently substituted N-tosyl-b-phenethylamines, under Lewis acids promotion. 11b,12 As shown in Table 1, submission of the N-sulfonyl heterocycles to microwave irradiation (490 Watts) provided good yields of the corresponding 3,4-dihydroisoquinolines upon a short reaction period (10-20 s), uncontaminated with the related isoquinolines; interestingly, however, increasing the irradiation time comple...