Stereochemistry of organometallic compound addition to ketones

Ashby, E. C.; Laemmle, J.

doi:10.1021/cr60296a005

Cited by 264 publications

(84 citation statements)

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“…Such divergent results obtained for the same reaction (Figure 2) cannot be interpreted in terms of any of the theories so far proposed to explain the facial selectivity of trigonal carbon centers, [1,16,17] but must be related to the different behavior of the reactive intermediates in the extraand intracomplex reactions.…”

Section: Discussionmentioning

confidence: 82%

“…Facial selectivity observed in condensed media has often been interpreted on the grounds of intrinsic stereoelectronic factors, which favor anti attack by nucleophilic reagents of both charged and neutral unsaturated carbon atoms of methylenecyclohexane derivatives and their carbonyl analogues. [1,16,17] This enthalpic approach assumes that entropic factors in the competing syn and anti processes are compensating or negligible, which can be accepted only in low-temperate investigations. The present investigation, along with a previous report in which the rigid 2-methyl-5-X-2-adamantyl cation (X F, Si(CH 3 ) 3 ) was used, suggests that facial selectivity of charged trigonal carbon centers in the gas phase is strongly influenced by entropic rather than enthalpic factors.…”

Section: Discussionmentioning

confidence: 99%

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Facial Selectivity of the (R)‐1,3‐Dimethyl‐1‐Cyclohexyl Cation in the Gas Phase

Filippi

2003

Chemistry A European J

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The model reaction between the (R)-1,3-dimethyl-1-cyclohexyl cation (I) and methanol has been investigated under gas-phase radiolytic conditions (750 Torr; 25-120 degrees C) with the aim of evaluating the intrinsic factors that govern the facial selectivity of biased carbocations. The peculiarity of the experimental approach allows the formation of different CH(3) (18)OH.I ionic adducts. Subsequent conversion of these adducts to give the corresponding E/Z covalent products follows different reaction coordinates, which are characterized by their own activation parameters. On the grounds of density functional theory (DFT) results, several [CH(3)OH.I] structures have been located on the relevant potential-energy surface (PES). The experimental results point to a gas-phase facial selectivity, which is mainly governed by entropic factors that arise as a result of the occurrence of different noncovalent ion-molecule "facial adducts" (FA). The formation of FAs may also play an important role in both the reaction dynamics and the positional selectivity. The present results cannot be interpreted by any of the models based on solution-phase experiments.

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Facial Selectivity of the (R)‐1,3‐Dimethyl‐1‐Cyclohexyl Cation in the Gas Phase

Filippi

2003

Chemistry A European J

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“…In a recently published review article on the stereochemistry of organometallic compound addition to cyclic ketones Ashby and Laemmle (6) concluded that the stereochemical outcome of the addition is primarily a function of the entering groups and steric requirements of the particular ketone, which are controlled by steric and torsional strain in the transition state. Factors such as solvent, nature of the metal to which the entering group is attached, and others, result in only minor changes in overall observed stereochemistry.…”

Section: Resultsmentioning

confidence: 99%

“…The ether extract was discarded and the aqueous phase was made basic with ammonium hydroxide and extracted with CH2C12, to give after drying and evaporation 0.65 g of an oil. The oil crystallized from acetone to give 0.34 g (49%) of 16a as a white solid; mp 261-263"C, nmr 6 …”

Section: 17-dimethyl-3-hydroxy-8-oxyisomorphina 16amentioning

confidence: 99%

5-Allyl-9-oxobenzomorphans. Part 4. Synthesis of 3-hydroxy-8-oxyisomorphinans, 5-allyl-9α-hydroxy-6,7-benzomorphans, and related tetrahydrofuranobenzomorphans

Lambert¹,

Daris²,

Monković³

1977

Can. J. Chem.

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A series of 3-hydroxy-8-oxyisomorphinans (11, 16) has been synthesized from the corresponding 5-allyl-9p-hydroxy-6,7-benzomorphans (7, 12) via a hydroboration, oxidation, mesylation, and cyclization sequence of reactions. Selective reduction of and methylmagnesium iodide addition to 5-allyl-2'-methoxy-2-methyl-9-oxo-6,7-benzomorphan (1) gave the respective 9a-hydroxy-6,7-benzomorphans (17). These were transformed to a number of 2-substituted-5-allyl-2',9~-dihydroxy-6,7-benzomorphans (22) and corresponding methyltetrahydrofurano analogs (24).

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“…For personal use only. , 1175rmn 'H (CDC1,) 6 : 0,87 (3H, t), 1,16 (6H, t), 1,02-1,50 (4H, m), 1,55-2,11 (5H, m), 2,49 (2H, m, H-2 et H-5a), 4,16 (4H, q) ppm; rmn I3C (CDC1,) 6 : 172,83, 171,73, 63,80, 60,95, 60,80,46,24, 34,68, 33,73, 31,02, 23,05, 21,73, 14,19 (3C) (CDC1,) 6 : 172,26,171,15,63,32,60,68,6034,46,00,34,34,30,87,30,69,30,62,22,81,22,65,14,00,13,88 (2C) Phe'nyl-2 cyclopentanedicarboxylate-1, 1 de ditthyle (39) : Rdt, 68% (0,199 g). Huile incolore; ir v,,, (film): 3045, 3020, 2980, 2965, 2910, 2880, 1730, 1600, 1500, 1470, 1455, 1380, 1370, 1300, 1265, 1230, 1205, 1080, 1055, 1100, 1080, 1060, 1030, 750, 700cm- 6 : 172,32, 170,35, 140,88, 128,46 (2C), 12739 (2C), 126,44, 65,44, 61,10, 60,63, 50,75, 35,00, 32,60, 24,21, 13,97, 13,35ppm; sm m/e: 291 (M+ + 1, 4%), 290 (M', Mhhyl-2 cyclohexanedicarboxylate-1, 1 de die'thyle (40) : Rdt, 55% (1,058 g).…”

Section: Partie Experimentalementioning

confidence: 99%

Étude de l'annélation à partir de dérivés dibromomés-1,4 et -1,5 en présence de carbanions

Canonne¹,

Plamondon²

1989

Can. J. Chem.

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Requ le 5 mai 1988 P. CANONNE et J. PLAMONDON. Can. J. Chem. 67, 555 (1989).Les dibromures primaires-secondaires ont Ct C prepares A partir des diols correspondants et employCs, avec des acides du carbone, pour la preparation de composCs cycliques disubstitues-1,2. L'utilisation d'un acide du carbone non-symmCtrique en presence de NaH dans le DME favorise une importante diasttrCostlection conduisant A la formation de l'isomkre trans. Les facteurs qui influencent la stCrCosClectivitC sont Cgalement proposes.Mots clPs: SN2 intramolCculaire, dCcarboxylation, acides alkyl-2 cycloalcanecarboxyliques-1, acides alkyl-1 indanecarboxyliques-2.P. CANONNE and J. PLAMONDON. Can. J. Chem. 67, 555 (1989).Primary-secondary dibromides have been prepared from the corresponding diols and used with carbon acids to prepare 1,2-disubstituted cyclic compounds. With unsymmetrical carbon acid in presence of NaH in DME, a high diastereoselection of the truns isomer is observed. Factors that affect the stereoselectivity are proposed.Key words: intramolecular SN2, decarboxylation, 2-alkylcycloalkanecarboxylic acids, I-alkylindan-2-carboxylic acids.Les travaux de recherche de notre laboratoire ont Ct C principalement axes sur 1'Claboration de systkmes cycliques. Nous avons utilisC les rkactifs de Grignard bisfonctionnels pour la synthkse des divers composCs polycycliques et spiranniques fonctionnalisCs (I). RCcemment nous avons Ctudit la stCrkochimie de la rCaction de Grignard intramolCculaire (2), en utilisant les organodimagnksiens primaires-secondaires, et nous avons prCpark stCrCosClectivement des composCs hydroxylks cycliques alkylts en position 2. En outre, l'introduction d'une fonction carboxylique nous a semblC d'un grand intkret (3), surtout pour son aspect stCrCochimique. Plus particulikrement, la synthkse des composCs 1 ,2-disubstitub en sCries cycloalcane et indane a attirC notre attention.Dans cette perspective de dkveloppement de mkthodologies intkressantes et rentables, nous nous sommes ainsi intkressCs a la recherche des conditions opkratoires permettant d'obtenir des acides alkylCs en position 2. En effet, la littkrature nous rCvkle que la formation la plus simple des acides mCthyl-2 cyclohexanecarboxyliques-1 est basCe sur la synthkse diCnique (4), alors que celle des acides mCthyl-2 cyclopentanecarboxyliques-1 (5) offre plusieurs possibilitks mais parait moins efficace. Par ailleurs, la synthkse des acides alkyl-2 cycloalcanecarboxyliques homologues ne semble pas &tre rapportCe dans la litttrature. Les mCthodes de synthese proposCes pour la prkparation des acides alkyl-1 indanecarboxyliques-2 sont encore moins satisfaisantes (6). Pour ces raisons, il nous a semblC important de trouver une mCthodologie gknkrale et efficace pour la prkparation de ces acides cycliques substituCs en position 2 et de leurs dtrivCs. Nous avons alors entrepris d'examiner la rCaction des dibromo-1,4 et -1 3 alcanes avec des acides du carbone, en fonction de la chaine hydrocarbonke et de la grandeur du cycle.Pour rkaliser une telle Ctude, nous av...

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Stereochemistry of organometallic compound addition to ketones

Cited by 264 publications

References 54 publications

Facial Selectivity of the (R)‐1,3‐Dimethyl‐1‐Cyclohexyl Cation in the Gas Phase

Facial Selectivity of the (R)‐1,3‐Dimethyl‐1‐Cyclohexyl Cation in the Gas Phase

5-Allyl-9-oxobenzomorphans. Part 4. Synthesis of 3-hydroxy-8-oxyisomorphinans, 5-allyl-9α-hydroxy-6,7-benzomorphans, and related tetrahydrofuranobenzomorphans

Étude de l'annélation à partir de dérivés dibromomés-1,4 et -1,5 en présence de carbanions

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