A new application of (PhO)3P-halogen-based reagents to the synthesis of vinyl halides and gem-dihalides is described. Vinyl halides were prepared in good to excellent yields from enolizable ketones, whereas aldehydes afforded the corresponding gem-dihalides. The halogenation proceeded smoothly under mild conditions.

Halogenation O 0235 A Mild Synthesis of Vinyl Halides and gem-Dihalides Using Triphenyl Phosphite-Halogen-Based Reagents. -The reaction of enolizable ketones efficiently provides vinyl halides, whereas starting from non-enolizable ketones and aldehydes gem-dihalides are obtained. -(SPAGGIARI, A.; VACCARI, D.; DAVOLI, P.; TORRE, G.; PRATI*, F.; J. Org. Chem. 72 (2007) 6, 2216-2219; Dip. Chim., Univ. Modena, I-41100 Modena, Italy; Eng.) -Jannicke 30-038

A novel application of (PhO) 3 P-Cl 2 chemistry to the synthesis of 2-substituted and 2,3-disubstituted pyrroles from N-allylamides is illustrated. A mild procedure is used to generate the imino chloride intermediates, which are subsequently cyclized to pyrroles. The products are smoothly obtained in moderate to good overall yields.

Pyrrole derivatives R 0120The Triphenyl Phosphite-Chlorine Reagent in the Synthesis of Pyrroles from N-Allylamides. -A novel and mild route to the 2-and 2,3-substituted pyrroles from allylamides is developed. The highest yields are obtained for the substrates (IIIc,d) bearing pentatomic heteroaromatic substituents. -(SPAGGIARI, A.; VACCARI, D.; DAVOLI, P.; PRATI*, F.; Synthesis 2006, 6, 995-998; Dip. Chim., Univ. Modena, I-41100 Modena, Italy; Eng.) -Y. Steudel 30-115

in recognition of his pioneering work in the chemistry of mind-altering alkaloids.Abstract: Substituted b-phenylethylamides undergo smooth intramolecular cyclization to 3,4-dihydroisoquinolines in good to excellent yields when treated with bromotriphenoxyphosphonium bromide at -60°C in dichloromethane in the presence of triethylamine. The reaction proceeds under the mildest conditions ever reported for Bischler-Napieralski-type cyclizations. When chlorotriphenoxyphosphonium choride is used, low yields are obtained instead.The isoquinoline skeleton features as the structural backbone in a plethora of alkaloids that occur typically, though by no means exclusively, in the plant kingdom, and which are endowed with a most impressive array of biological and pharmacological activities. 1,2 Far back in 1893, Bischler and Napieralski paved the way to the synthesis of isoquinoline alkaloids by succeeding in preparing simple 3,4-dihydroisoquinolines by dehydration of b-phenylethylamides with either P 2 O 5 or ZnCl 2 at temperatures above 250°C. 3 Ever since, this reaction, which has been traditionally referred to as the BischlerNapieralski cyclization, 4 has represented one of the most general methods for the construction of isoquinoline scaffolds en route to the total synthesis of natural alkaloids, in addition to the similarly useful and somewhat complementary Pictet-Spengler cyclization which, by contrast, is usually preferred when the 1,2,3,4-tetrahydroisoquinoline scaffold is desired instead. 5In the Bischler-Napieralski reaction, a suitable halogenating agent brings about the activation of the starting b-arylethylamide into an iminoyl chloride species which rearranges to a nitrilium ion intermediate that subsequently undergoes intramolecular electrophilic aromatic substitution. 6 In general, common reagents for the reaction are represented by POCl 3 , 7 P 2 O 5 -POCl 3 , 8 polyphosphoric acid-POCl 3 , 9 P 2 O 5 -pyridine, 10 polyphosphate esters, 11 phosphonitrilic chloride, 12 as well as less conventional systems such as POCl 3 in ionic liquids 13 or acidic zeolites. 14 However, heating at reflux in toluene or, at the very best, acetonitrile, is always required. Although all these methods are operatively simple, the harsh reaction conditions may result detrimental, especially when sensitive functional groups are resident. To circumvent such limitations, milder reaction conditions under which BischlerNapieralski-type cyclizations can be performed have also been developed. These include, for instance, triphosgene, 15 (COCl) 2 /FeCl 3 in dichloromethane, 16 Ph 3 P in refluxing CCl 4 17 or, in the case of 3,4-dihydroisoquinolones, Tf 2 O/DMAP 18 or AlCl 3 / KI. 19 In the course of our studies on mild activation of amides using chlorotriphenoxyphosphonium chloride, viz. (PhO) 3 P + ClCl -(TPPCl 2 ), 20 indolamides were found to undergo efficient Bischler-Napieralski-type intramolecular cyclization, which allowed us to disclose a very mild and straightforward access to 3,4-dihydro-b-carbolines in good to excellent yield...