José L. García-Navío

One-pot Graebe-Ullmann synthesis of γ-carbolines under microwave irradiation

Abstract One-pot efficient and simple synthesis of γ-carboline derivatives by the Graebe-Ullmann method was conducted in a commercial microwave oven in a few minutes at a low energy level and using erlenmeyer as adequate reaction vessels. Yields are similar to those obtained by conventional heating.

Azinium-N-(2′-azinyl)aminides: synthesis, structure and reactivity

Abstract Several azinium-N-(2′-azinyl)aminides are reported. The structure of pyridinium-N-(2′-pyridyl)aminide has been studied, both in solution and in crystalline state, and results have been compared. In non-polar solvents, the aminides present a planar conformation stabilized by an intramolecular hydrogen bond. The reactivity toward electrophiles confirms the structural data, producing either N- or C- substitutions under mild conditions.

Pyridinium-N-(2-pyridyl)aminides : a selective approach to substituted 2-aminopyridines

Abstract Differently substituted 2-aminopyridines have been prepared in two steps from pyridinium-N-(2-pyridyl)aminide, by reaction with the corresponding elect

New uses of Westphal condensation: Synthesis of flavocorylene and related indolo[2,3-a]quinolizinium salts.

Abstract Using the Westphal condensation, flavocorylene and related Indolo[2,3-a]-quinolizinium salts have been prepared in two steps, starting from commercially available β-carboline derivatives.

New uses of the westphal condensation. Synthesis of pi-donor-pi-acceptor heterocycles

Authors wish to acknowledge the assistance provided by LILLY S.A. in Nmr analysis, and to the Comision Interministerial de Ciencia y Tecnologia (CICYT) for financial support ( Project PB87-0755J

N-(Pyridylmethyl)azinium Salts: Precursors of Pyridyl-stabilised Azinium N-Ylides

Abstract A series of new N-(pyridylmethyl)azinium salts have been synthesized from 2, 4, 6-triphenylpyrylium tetrafluoroborate. Generation of azinium N-ylides in the presence of base, has been proved by reactions with electrophiles, such as carbon disulphide, phenyl isothiocyanate and with acetylene dipolarophiles.

Heterosryl Stabilised Azinium Yields. 1,3,4-Thiadiazole as Stabilising Group

Reaction of 1-[(1,3,5-thiadiazol-2-yl)]-methylpyridinium derivatives with diverse electrophiles produced disubstituted heteroarylmethylpyridinium ylides. Only with phenyl isothiocyanate 1,3-dipolar cycloaddition was observed

Unexpected highly regioselective macrocyclization of o-allylic N-carbonyl substituted anilines

An unexpected bromocyclocarbamoylation of o -allylic N -BOC-anilines has been observed producing 2-oxo-3,1-benzoxazocine derivatives through an 8- endo - trig process, which on heating ring-transformed into a [6.5.5] tricyclic fused oxazolidinone compounds. A mixture of both heterocycles was obtained when the starting N -BOC anilines were heated with NBS in THF. The process seems to be general for related N -carbonyl substituted anilines.

Optimized Synthesis of Di, Tri and Tetrafused Pyridazinium Cations

Abstract By combining two complementary statistical techniques (fractional factorial experimental design and simplex operation) the synthesis of the parent pyrido[1,2- b ]-pyridazinium cation has been successfully carried out (the yield was improved from less than 10 to 65%) by basic condensation of 2-methyl-1-aminopyridinium mesitylenesulfonate and [1,4]dioxane-2,3-diol. Using the optimized reaction conditions, other related heterocyclic cations could be prepared, and two interesting examples are now reported.

A straightforward synthesis of 4-substituted 3,4-dihydro-1H-2,1,3-benzothiadiazine 2,2-dioxides

4-Substituted 3,4-dihydro-1H-2,1,3-benzothiadiazine 2,2-dioxides 11 have been efficiently prepared in two steps from the suphamide 9 by condensation of anion II, derived from 9 by metal–halogen exchange, with aromatic and aliphatic aldehydes and cyclodehydration of the so-formed alcohols 10 under acidic conditions.