Un procedimiento para preparar este compuesto. Una composicion fungicida que comprende un compuesto de formula general (1). Un método para tratar plantas mediante la aplicacion de un compuesto de formula general (1) o una composicion que lo comprende Reivindicacion 1: Un compuesto de formula general (1), en la que: n es 1, 2, 3 o 4; X es un átomo de halogeno, un grupo nitro, ciano, hidroxi, amino, sulfanilo, pentafluoro-gamma6-sulfanilo, formilo, formiloxi, formilamino, carboxi, carbamoílo, N-hidroxicarbamoílo, un grupo carbamato, un grupo (hidroxiimino)-alquilo C1-6, alquil C1-8-amino, alcoxi C1-8), haloalquilo C1-6, tri(alquil C1-8)sililo, alquil C1-8-amino, di alquil C1-8-amino, alcoxi C1-8, halogenoalcoxi C1-8 con 1 a 5 átomos de halogeno, [alquil C1-8]sulfanilo, halogeno[alquil C1-8]sulfanilo con 1 a 5 átomos de halogeno, alquenil C2-8-oxi, halogeno[alquenil C2-8]oxi con 1 a 5 átomos de halogeno, [alquinil C3-8]oxi, halogeno[alquinil C3-8]oxi con 1 a 5 átomos de halogeno, cicloalquilo C3-8, halogenocicloalquilo C3-8 con 1 a 5 átomos de halogeno, [alquil C1-8]carbonilo, halogeno[alquil C1-8]carbonilo con 1 a 5 átomos de halogeno, [alquil C1-8]carbamoílo, di[alquil C1-8]carbamoílo, N-[alquil C1- 8]oxicarbamoílo, [alcoxi C1-8]carbamoílo, N-[alquil C1-8]-[alcoxi C1-8]carbamoílo, alcoxi [C1-8]carbonilo, halogeno[alcoxi C1-8]carbonilo con 1 a 5 átomos de halogeno, [alquil C1-8]carboniloxi, halogeno[alquil C1-8]carboniloxi con 1 a 5 átomos de halogeno, [alquil C1-8]carbonilamino, halogeno[alquil C1-8]carbonilamino con 1 a 5 átomos de halogeno, [alquil C1-8]aminocarboniloxi, di[alquil C1-8]aminocarboniloxi, [alquil C1-8]oxicarboniloxi, [alquil C1-8]sulfenilo, halogeno[alquil C1- 8]sulfenilo con 1 a 5 átomos de halogeno, [alquil C1-8]sulfinilo, halogeno[alquil C1-8]sulfinilo con 1 a 5 átomos de halogeno, [alquil C1-8]sulfonilo, halogeno[alquil C1-8]sulfonilo con 1 a 5 átomos de halogeno, [alcoxi C1-6]-imino, [alcoxi C1-6- imino]-alquilo C1-6, [alquenil C1-6-oxiimino]-alquilo C1-6), [alquinil C1-6-oxiimino]-alquilo C1-6, (benciloxiimino)-alquilo C1-6, benciloxi, bencilsulfanilo, bencilamino, fenoxi, fenilsulfanilo o fenilamino; A es un átomo de O, un grupo NR4, S, sulfinilo sulfonilo o SiR4R5; R1 y R2 se eligen independientemente uno del otro para que sean un átomo de H, halogeno, ciano, hidroxi, amino, sulfanilo, formilo, formiloxi, formilamino, carboxi, carbamoílo, N-hidroxicarbamoílo, carbamato, hidroxi- imino-alquilo C1-6, alquilo C1-6, alquenilo C2-6, alquinilo C2-6 u tri(alquil C1-8)sililo, alquil C1-6-amino, dialquil C1-6-amino, alcoxi C1-6, halogenoalquilo C1-6 con 1 a 5 átomos de halogeno, halogenoalcoxi C1-6 que tiene de 1 a 5 átomos de halogeno, alquil C1-6-sulfanilo, halogenoalquil C1-6-sulfanilo que tiene 1 a 5 átomos de halogeno, alquenil C2-6-oxi, halogenoalquenil C2-6-oxi que tiene de 1 a 5 átomos de halogeno, alquinil C3-6-oxi, halogenoalquinil C3-6-oxi que tiene de 1 a 5 átomos de halogeno, cicloalquilo C3-6, halogenocicloalquilo C3-6 que tiene de 1 a 5 átomos de halogeno, alquil C1-6-carbonilo, halogenoalquil C1-6-carbonilo que tiene de 1 a 5 átomos de halogeno, alquil C1-6-carbamoilo, dialquil C1-6-carbamoilo, N- alquil C1-6-oxicarbamoílo, alcoxi C1-6-carbamoílo, N-alquil C1-6-alcoxi C1-6-carbamoílo, alcoxi C1-6-carbonilo, halogenoalcoxi C1-6-carbonilo que tiene de 1 a 5 átomos de halogeno, alquil C1-6-carboniloxi, halogenoalquil C1-6-carboniloxi que tiene de 1 a 5 átomos de halogeno, alquil C1-6 carbonilamino, halogenoalquil C1-6-carbonilamino que tiene de 1 a 5 átomos de halogeno, alquil C1-6-aminocarboniloxi, dialquil C1-6-aminocarboniloxi, alquil C1-6-oxicarboniloxi, alquil C1-6-sulfenilo, halogenoalquil C1-6-sulfenilo que tiene de 1 a 5 átomos de halogeno, alquil C1-6-sulfonilo, halogenoalquil C1-6-sulfonilo que tiene de 1 a 5 átomos de halogeno, bencilo, benciloxi, bencilsulfanilo, bencilsulfinilo, bencilsulfonilo, bencilamino, fenoxi, fenilsulfanilo, fenilsulfinilo, fenilsulfonilo, fenilamino, fenilcarbonilamino o fenilo; con la condicion de que R1 y R2 no sean ambos un grupo hidroxi; R3 es un átomo de H, alquilo C1-6 o cicloalquilo C3-7; R4 y R5 se seleccionan independientemente uno del otro para que sean un átomo de hidrogeno, o un alquilo C1-6; y Het representa un heterociclo no condensado de 5, 6 o 7 elementos con uno, dos o tres heteroátomos que pueden ser iguales o diferentes, estando Het unido por un átomo de C y estando Het sustituido por uno o más sustituyentes seleccionados de entre un átomo de halogeno, un grupo nitro, ciano, sulfanilo, pentafluoro-gamma6-sulfanilo, alquilo C1-8, halogenoalquilo C1-8 que tiene 1 a 5 átomos de halogeno, alquenilo C2-8, alquinilo C2-8, alcoxi C1-8, halogenoalcoxi C1-8 que tiene 1 a 5 átomos de halogeno, alcoxi C1-8-alquenilo C2-8, alquil C1-8-sulfanilo, o un halogenoalquil C1-8-sulfanilo con 1 a 5 átomos de halogeno, así como sus sales, N-oxidos, complejos metálicos, complejos metaloides e isomeros opticamente activos. Reivindicacion 11: Un procedimiento para la preparacion de un compuesto de formula general (1) como se definio en la reivindicacion 1, que comprende hacer reaccionar un derivado de la N-metil carboxamida de formula general (2) o una de sus sales: en la que: Het, R1, R2 y R3 son como se definieron en la reivindicacion 1; U es un grupo saliente que se elige para que sea un átomo de halogeno, un grupo hidroxilo, - Ora, -OCORa, siendo Ra un alquilo C1-6, haloalquilo C1-6, bencilo, 4-metoxibencilo, o un grupo pentafluorofenilo; en que X, n y A son como se definieron anteriormente; en presencia de una base.A procedure to prepare this compound. A fungicidal composition comprising a compound of general formula (1). A method of treating plants by applying a compound of general formula (1) or a composition comprising it Claim 1: A compound of general formula (1), wherein: n is 1, 2, 3 or 4; X is a halogen atom, a nitro, cyano, hydroxy, amino, sulfanyl, pentafluoro-gamma6-sulfanyl, formyl, formyloxy, formylamino, carboxy, carbamoyl, N-hydroxycarbamoyl, a carbamate group, a (hydroxyimino) -alkyl group C1-6, C1-8-amino alkyl, C1-8 alkoxy), C1-6 haloalkyl, tri (C1-8 alkyl) silyl, C1-8-amino alkyl, di C1-8-amino alkyl, C1-8 alkoxy , C1-8 halogenoalkoxy with 1 to 5 halogen atoms, [C1-8 alkyl] sulfanyl, halogen [C1-8 alkyl] sulfanyl with 1 to 5 halogen atoms, C2-8-oxy alkenyl, halogen [C2-8 alkenyl] ] oxy with 1 to 5 halogen atoms, [C3-8 alkynyl] oxy, halogen [C3-8 alkynyl] oxy with 1 to 5 halogen atoms, C3-8 cycloalkyl, C3-8 halogenocycloalkyl with 1 to 5 halogen atoms , [C1-8 alkyl] carbonyl, halogen [C1-8 alkyl] carbonyl with 1 to 5 halogen atoms, [C1-8 alkyl] carbamoyl, di [C1-8 alkyl] carbamoyl, N- [C1-8 alkyl] oxycarbamoyl, [C1-8 alkoxy] carbamoyl, N- [C1-8 alkyl] - [C1-8 alkoxy] carbamoyl, [C1-8] alkoxy carboni lo, halogen [C1-8 alkoxy] carbonyl with 1 to 5 halogen atoms, [C1-8 alkyl] carbonyloxy, halogen [C1-8 alkyl] carbonyloxy with 1 to 5 halogen atoms, [C1-8 alkyl] carbonylamino, halogen [C1-8 alkyl] carbonylamino with 1 to 5 halogen atoms, [C1-8 alkyl] aminocarbonyloxy, di [C1-8 alkyl] aminocarbonyloxy, [C1-8 alkyl] oxycarbonyloxy, [C1-8 alkyl] sulfenyl, halogen [C1-8 alkyl] sulfenyl with 1 to 5 halogen atoms, [C1-8 alkyl] sulfinyl, halogen [C1-8 alkyl] sulfinyl with 1 to 5 halogen atoms, [C1-8 alkyl] sulfonyl, halogen [alkyl C 1-8] sulfonyl with 1 to 5 halogen atoms, [C 1-6 alkoxy] -imino, [C 1-6 alkoxy] -C 1-6 alkyl, [C 1-6 alkenyl-oxyimino] -C 1-6 alkyl) , [C 1-6 alkynyl-oxyimino] -C 1-6 alkyl, (benzyloxyimino) -C 1-6 alkyl, benzyloxy, benzylsulfanyl, benzylamino, phenoxy, phenylsulfanyl or phenylamino; A is an O atom, an NR4, S, sulfinyl sulfonyl or SiR4R5 group; R1 and R2 are independently selected from each other to be an atom of H, halogen, cyano, hydroxy, amino, sulfanyl, formyl, formyloxy, formylamino, carboxy, carbamoyl, N-hydroxycarbamoyl, carbamate, hydroxyimino-C1-alkyl 6, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl or tri (C 1-8 alkyl) silyl, C 1-6 alkyl, C 1-6 dialkyl, C 1-6 alkoxy, C 1-6 halogenoalkyl with 1 to 5 halogen atoms, C1-6 halogenoalkoxy having 1 to 5 halogen atoms, C1-6-sulfanyl alkyl, halogen C1-6-sulfanyl alkyl having 1 to 5 halogen atoms, C2-6-oxi alkenyl, C2-6-oxy halogenoalkenyl having 1 to 5 halogen atoms, C3-6-oxy alkynyl, C3-6-oxy halogenoalkyl having 1 to 5 halogen atoms, C3-6 cycloalkyl, C3-6 halocycloalkyl having from 1 to 5 halogen atoms, C1-6 alkylcarbonyl, halogeno C1-6 alkylcarbonyl having 1 to 5 halogen atoms, C1-6 alkylcarbamoyl, C1-6 dialkyl carbamoyl, N- C1- alkyl 6-oxicarbamoyl, alco xi C1-6-carbamoyl, N-C1-6 alkyl-C1-6 alkoxy-carbamoyl, C1-6 alkoxycarbonyl, C1-6 halogenoalkoxy having 1 to 5 halogen atoms, C1-6 alkylcarbonyloxy , halogenoalkyl C1-6-carbonyloxy having 1 to 5 halogen atoms, C1-6 alkyl carbonylamino, halogenoalkyl C1-6-carbonylamino having 1 to 5 halogen atoms, C1-6 alkylcarbonyloxy, C1-6 dialkyl -aminocarbonyloxy, C1-6 alkyl-oxycarbonyloxy, C1-6 alkyl sulfenyl, halogeno C1-6 alkyl sulfenyl having from 1 to 5 halogen atoms, C1-6 alkyl sulfonyl, halogen C1-6 alkyl sulfonyl having 1 at 5 halogen, benzyl, benzyloxy, benzylsulfanyl, benzylsulfinyl, benzylsulfonyl, benzylamino, phenoxy, phenylsulfanyl, phenylsulfinyl, phenylsulfonyl, phenylamino, phenylcarbonylamino or phenyl atoms; with the proviso that R1 and R2 are not both a hydroxy group; R3 is an atom of H, C1-6 alkyl or C3-7 cycloalkyl; R4 and R5 are independently selected from each other to be a hydrogen atom, or a C1-6 alkyl; and Het represents an uncondensed heterocycle of 5, 6 or 7 elements with one, two or three heteroatoms that may be the same or different, with Het being joined by a C atom and Het being substituted by one or more substituents selected from one atom. halogen, a nitro, cyano, sulfanyl, pentafluoro-gamma6-sulfanyl, C1-8 alkyl, halogen C1-8 alkyl group having 1 to 5 halogen atoms, C2-8 alkenyl, C2-8 alkynyl, C1-8 alkoxy group, C1-8 halogenoalkoxy having 1 to 5 halogen atoms, C1-8 alkoxyC2-8 alkenyl, C1-8 alkyl sulfanyl, or a halogen C1-8 alkyl sulfanyl with 1 to 5 halogen atoms, as well as their salts , N-oxides, metal complexes, metalloid complexes and optically active isomers. Claim 11: A process for the preparation of a compound of general formula (1) as defined in claim 1, which comprises reacting a N-methyl carboxamide derivative of general formula (2) or a salt thereof: which: Het, R1, R2 and R3 are as defined in claim 1; U is a leaving group that is chosen to be a halogen atom, a hydroxyl group, - Ora, -OCORa, where Ra is a C1-6 alkyl, C1-6 haloalkyl, benzyl, 4-methoxybenzyl, or a pentafluorophenyl group; in which X, n and A are as defined above; in the presence of a base.