Intramolecular reaction

About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.

The intramolecular Buchner reaction of aryl diazoketones. Substituent effects and scope in synthesis

Abstract: Rhodium(II) acetate-catalysed cyclisation of α-diazoketones derived from 3-arylpropionic acid produces bicyclo[5.3.0]decatrienones or 2-tetralones depending on the substitution pattern of the aryl ring in the precursor; the former products are transformed into the latter catalytically with trifluoroacetic acid. Precursors with methyl, methoxy, and acetoxy substituents have been examined, efficient cyclisation occurring in all cases. When the precursor contains a meta-methoxy substituent, 2-tetralones are obtained directly. The efficient conversion of 3-phenylpropionic acid into trans-1-methylbicyclo[5.3.0]decan-2-one is also described, partial asymmetric synthesis having been realised through the use of rhodium (S)-mandelate as the cyclisation catalyst. Cyclisations of diazoketones derived from 4-phenylbutyric acid and 5-phenylpentanoic acid have also been studied; the former provides a new entry into the bicyclo[5.4.0]undecane system whereas the latter produces a 2,3-disubstituted cyclopentanone via C–H insertion. Aspects of the cycloheptatriene-norcaradiene equilibrium in fused ring systems are discussed.

Inter- and intramolecular excited-state interactions of surfactant-active rhenium(I) photosensitizers

Abstract: Etude detaillee de [(bpy)Re(CO) 3 NC(CH 2 ) n CH 3 ] + n=0-17: interactions avec des micelles (CTAB) et des cyclodextrines

Intramolecular interactions between chalcogen atoms: organoseleniums derived from 1-bromo-4-tert-butyl-2,6-di(formyl)benzene.

Abstract: [structure: see text] The synthesis and characterization of a series of low-valent organoselenium compounds derived from 1-bromo-4-tert-butyl-2,6-di(formyl)benzene (22) is described The synthesis of diselenide 25 was achieved by the lithiation route whereas bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) was synthesized by treating 22 with disodium diselenide A series of monoselenides (27, 28, and 29) was obtained by facile nucleophilic substitution of bromine in 22, using the corresponding selenolates as nucleophiles The halogenation reactions of bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) did not afford the corresponding selenenyl halides but resulted in the isolation of an unexpected cyclic selenenate ester 34 as a product The selenide 32 was synthesized by the treatment of dimethoxymethyl diselenide with trilithiated 2-bromo-5-tert-butyl-N,N'-di(phenyl)isophthalamide The existence of potential SeO intramolecular nonbonding interactions was examined by IR, (1)H, and (77)Se NMR spectroscopy, X-ray crystallography, and computational studies The X-ray crystal structures of 26 and 27, having two ortho formyl groups, reveal the absence of any SeO interactions However, the SeO interactions were observed in the selenenate ester 34 where one of the formyl groups has been utilized for the selenenate ring formation The crystal structures of 26 and 27 exhibited intermolecular short-range C-HSe interactions (hydrogen bonding) Although there are four heteroatoms in carbamoyl moieties ortho to selenium capable of forming a five-membered ring on intramolecular coordination, no such intramolecular SeX (X = N, O) interaction was observed in the crystal structure of 32 The density functional theory calculations at the B3LYP/6-31G* level predicted that for all the diformyl systems (47a-c, 48a-c), the anti,anti conformer (when both formyl oxygen atoms point away from the selenium) is more stable This preference was found to be reversed in the monoformyl-substituted systems (50a,b, 51a,b), where the syn conformer (when formyl oxygen is near the selenium) is energetically more favorable than the anti conformer

New synthesis of nitrogen heterocycles through amide-directed hydrocarbonylation of alkenamides catalyzed by rhodium complexes

Abstract: Amide-directed hydrocarbonylation of 3-butenamide(1) catalyzed by rhodium complexes such as RhCl(PPh 3 ) 3 , RhCl(CO)(PPh 3 ) 2 , HRh(CO)(PPh 3 ) 3 , and Rh 4 (CO) 12 gives a mixture of 3,4-dihydro-2-pyridone (2), 4-methyl-3-pyrrolin-2-one (3), and a unique heterodimer, 6-(4-methyl-2-oxo-3-pyrrolin-1-yl)-2-piperidone (4)

Diastereoselection in the formation of spirocyclic oxindoles by the intramolecular Heck reaction.

Abstract: Diastereoselective double Heck cyclizations of cyclohexene diamides 1 and 3 form contiguous quaternary stereocenters, with diastereoselection being controlled by the trans-diol protecting group. In this, the first in a series of two papers, the origin of diastereoselection in the first ring-closure step of these reactions is examined. Nine simplified analogues of 1 and 3 were synthesized and cyclized to discern what structural features are required to realize high diastereoselection in the first intramolecular Heck reaction. These studies show that high stereoselection (>20:1) does not arise from a single structural feature: it is seen only in substrates that contain both a trans-acetonide and a tertiary amide substituent at C2. Two subtle factors appear to be involved: (1) Avoidance of eclipsing interactions between the forming C−C bond and the pseudoaxial hydrogen atom at C6 and between the pseudoequatorial hydrogen atom at C6 and the carbonyl carbon of the forming spirooxindole. (2) The vinylic amide...