ABSTRACT
Concentrations of four monoterpenes were determined in needles of Pinus radiata (D.Don) (Pinales: Pinaceae) trees that were attacked or nonattacked by Tomicus piniperda (L.) (Coleoptera: Scolytinae). Compounds were identified and quantified by gas chromatography-mass spectrometry. The mean ambient temperature was obtained using climate-recording data loggers. The effect of limonene on field aggregation was also evaluated at three limonene release rates using Lindgren attractant-baited traps and trap logs. Attacked trees produced less α-pinene in March, July, and November than nonattacked trees, less ß-pinene in July and November, and less limonene from May to November. Limonene reduced the attraction of T. piniperda to attractant-baited traps and trap logs. Results were linked to better responses to high temperatures, with respect to terpene contents, by the nonattacked trees after the spring attack.
Subject(s)
Animal Distribution/drug effects , Coleoptera/drug effects , Cyclohexenes/pharmacology , Monoterpenes/metabolism , Pinus/metabolism , Terpenes/pharmacology , Animals , Cyclohexenes/analysis , Insect Repellents/analysis , Insect Repellents/metabolism , Limonene , Monoterpenes/analysis , Pheromones/analysis , Pheromones/metabolism , Pinus/chemistry , Seasons , Terpenes/analysisABSTRACT
A concise and eco-friendly synthesis of highly functionalized 1,2-oxazines from phosphinyl- and phosphonyl-nitroso alkenes has been developed. The key step of this process, which involves a two-step sequence of reactions on-water, is a regioselective hetero-Diels-Alder cycloaddition reaction of enol ethers to 4-phosphinyl or 4-phosphonyl nitroso alkenes mediated by water itself. The process has also been performed under solvent-free conditions and in organic solvents for comparison.
Subject(s)
Alkenes/chemistry , Ethers/chemistry , Nitroso Compounds/chemistry , Oxazines/chemical synthesis , Solvents/chemistry , Water/chemistry , Catalysis , Cycloaddition Reaction , Molecular Structure , Oxazines/chemistry , Phosphorylation , StereoisomerismABSTRACT
Phosphorylated nitroso alkenes react with cyclic dienes such as cyclopentadiene or cyclohexadiene to afford hetero Diels-Alder-type cycloadducts where the nitroso alkene participates as dienophile component and the cyclic olefin acts as the 4π-electron (diene) system. Subsequent aza-Cope rearrangement affords highly functionalized 5,6-dihydro-4H-1,2-oxazines. Conversely, the reaction of TMS-substituted cyclopentadiene (dienophile) with nitroso alkenes as heterodienes leads directly to bicyclic 1,2-oxazines. Theoretical studies are in agreement with the experimental results and with the new aza-Cope rearrangement proposed.
Subject(s)
Alkenes/chemistry , Nitroso Compounds/chemistry , Organophosphorus Compounds/chemistry , Phosphines/chemistry , Catalysis , Molecular Structure , StereoisomerismABSTRACT
The synthesis of highly functionalized N-hydroxypyrrole derivatives by the formal [3+2] cycloaddition reaction of enamines and nitroso alkenes derived from phosphine oxides and phosphonates is reported. Intermediate phosphorylated nitrones, whose formation can be explained by a conjugate addition of enamines to phosphorylated nitroso alkenes and formation of the five-membered heterocycles, are isolated.
Subject(s)
Alkenes/chemistry , Amines/chemistry , Organophosphorus Compounds/chemistry , Pyrroles/chemistry , Stereoisomerism , Substrate SpecificityABSTRACT
Aza-Michael reaction of ammonia, aliphatic, aromatic and optically active amines to an alpha,beta-unsaturated imine derived from alpha-aminophosphonate affords alpha-dehydroaminophosphonates with a gamma-stereogenic center bearing an amino group. Resulting gamma-amino alpha-dehydroaminophosphonates can be used for the preparation of phosphorylated pyrimidine derivatives.
Subject(s)
Amines/chemistry , Imines/chemistry , Organophosphonates/chemistry , Organophosphonates/chemical synthesis , Pyrimidines/chemical synthesis , Cyclization , Molecular Structure , Pyrimidines/chemistry , StereoisomerismABSTRACT
The synthesis of substituted N-acetyl- and N-aroyl-2-pyrazolines via intramolecular Michael addition of alpha,beta-unsaturated hydrazones generated through olefination of phosphinyl and phosphonyl hydrazones with carbonyl compounds is reported. The regioselective reduction of the C-N double bond in these 2-pyrazolines using Superhydride (Et3BHLi) gives pirazolidine derivatives with excellent levels of cis-diastereoselectivity. These 2-pyrazolines can also be obtained in one-pot reaction from allenes, hydrazides, and aldehydes; and pyrazolidines, after reduction, from allenes, hydrazides, and aldehydes. This synthetic route was developed to provide a new approach to substituted azaproline derivatives in a diastereoselective fashion.
Subject(s)
Aza Compounds/chemical synthesis , Proline/analogs & derivatives , Proline/chemical synthesis , Pyrazoles/chemistry , Pyrazoles/chemical synthesis , Aza Compounds/chemistry , Cyclization , Molecular Structure , Proline/chemistry , StereoisomerismABSTRACT
The synthesis of nitrosoalkenes derived from phosphine oxides and phosphonates generated through base-mediated dehydrohalogenations of readily available alpha-halooximes is reported. These highly reactive intermediates act as Michael acceptors toward nucleophilic reagents such as ammonia, amines, and optically active amino esters, furnishing alpha-amino phosphine oxides and phosphonates in a highly regioselective fashion.
Subject(s)
Alkenes/chemistry , Amines/chemistry , Nitrogen/chemistry , Organophosphonates/chemistry , Oxides/chemistry , Phosphines/chemistry , Alkenes/chemical synthesis , Ammonia/chemistry , Aza Compounds/chemistry , Esters/chemistry , Halogens/chemistry , Hydrogen/chemistry , Molecular Structure , Oximes/chemistry , PhosphorylationABSTRACT
An efficient synthesis of alpha,beta-unsaturated imines derived from alpha-aminophosphonates is achieved through aza-Wittig reaction of P-trimethyl phosphazenes with beta,gamma-unsaturated alpha-ketophosphonates. Selective 1,2-reduction of such 1-azadienes affords beta,gamma-unsaturated alpha-aminophosphonates, phosphorylated analogs of vinylglycines, which are hydrogenated to yield saturated alpha-aminophosphonate derivatives.
Subject(s)
Imines/chemistry , Organophosphonates/chemistry , Molecular Structure , Oxidation-Reduction , PhosphorylationABSTRACT
An efficient synthesis of 1-azadienes derived from alpha-aminoesters is achieved through an aza-Wittig reaction of phosphazenes with beta,gamma-unsaturated alpha-ketoesters. Regioselective 1,2-reduction of these functionalized 1-azadienes affords vinylglycine derivatives, while conjugative 1,4-reduction gives alpha-dehydroamino acid compounds. Reduction of both the carbon-carbon and the imine-carbon-nitrogen double bonds leads to the formation of alpha-amino acid derivatives.
ABSTRACT
The preparation of tetrahydropyrazines, dihydropyrazines, pyrazines, piperazinones, and quinoxalines by 1,4-addition of 1,2-diamines to 1,2-diaza-1,3-butadienes bearing carboxylate, carboxamide, or phosphorylated groups at the terminal carbon and subsequent internal heterocyclization is described. The solvent-free reaction of carboxylated 1,2-diaza-1,3-butadienes with the same reagents affords piperazinones, while phosphorylated 1,2-diaza-1,3-butadienes yield phosphorylated pyrazines. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-diamines produces pyrazines.
Subject(s)
Amines/chemistry , Aza Compounds/chemistry , Piperazines/chemistry , Pyrazines/chemistry , Quinoxalines/chemistry , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Structure , Piperazine , Solutions , SolventsABSTRACT
A simple and efficient asymmetric synthesis of 2H-azirine-2-phosphine oxides 3 is described. The key step is a solid-phase bound achiral or chiral amine-mediated Neber reaction of beta-ketoxime tosylates derived from phosphine oxides 1. Reaction of 2H-azirines 3 and 11 with carboxylic acids 4 gives phosphorylated ketamides 5 and 12. Ring closure of ketamides 5 and 12 with triphenylphosphine and hexachloroethane in the presence of triethylamine leads to the formation of phosphorylated oxazoles 8 and 13.