Solvomercuration-demercuration. 8. Oxymercuration-demercuration of methoxy-, hydroxy-. and acetoxy-substituted alkenes

Brown, Herbert C.; Lynch, Gary J.

doi:10.1021/jo00316a011

Cited by 39 publications

(13 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Whereas 14 yields the two exo-alcohols 26 a and (20) gives only a small amount of the expected exo-alcohol25 d, the major product being 2-endo-hydroxynorbornane, formed by rearrangement and subsequent reduction during workup. The regioselective oxymercuration of the 1-(methoxymethy1)norbornene 18 is very similar to that of the methoxymethylolefin 27 [13] ( Table 4 ) . The high regioselectivity observed in both cases, however, needs further interpretation (see below).…”

Section: Synthesis Of Precursors Andmentioning

confidence: 74%

Hydroboration and Oxymercuration of Some 1‐Substituted Norborn‐2‐enes

Luef

Vögeli

Keese

1983

Helvetica Chimica Acta

View full text Add to dashboard Cite

show abstract

Section: Synthesis Of Precursors Andmentioning

confidence: 74%

Hydroboration and Oxymercuration of Some 1‐Substituted Norborn‐2‐enes

Luef

Vögeli

Keese

1983

Helvetica Chimica Acta

View full text Add to dashboard Cite

show abstract

“…Cooling to room temperature and then to 0 °C afforded 263 mg (87%) of fine white needles (mp 84-85 °C): NMR (CDCls) <5 7.18 (t, 1H, J = 8 Hz), 6.99 (m, 3H), 3.62 (m, 1H), 2.60 (t, 2H, J = 7 Hz), 2.54 (m, 2H), 1.2-1.85 (m, 16H), 1.21 (s, 6H), 1.00 (s, 3H); 13C NMR (CDC13) <5 (mult) 143.2 (s), 142.6 (s), 128.3 (d), 128.1 (d), 125.5 (d), 70.9 (s), 70.6 (d), 46.2 (t), 43.6 (t), 35.8 (t), 35.0 (t), 32.1 (s), 32.0 (t), 30.9 (t), 30.1 (t), 29.1 (q), 24.0 (t), 22.5 (q); IR (film, cm*1) 3350 brd, 1607,1588, 1367, 1151, 1065, 700; MS m/z (rel intensity) no M+ in El spectrum, 315 (12), 314 (51), 244 (14), 145 (20), 117 (33), 105 (24), 95 (100); exact mass caled for C22H37O2 333.2793 (M + 1, FAB), found 333.2805. Anal.…”

Section: Methodsmentioning

confidence: 99%

Design and Synthesis of Seco-oxysterol Analogs as Potential Inhibitors of 3-Hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) Reductase Gene Transcription

et al. 1994

View full text Add to dashboard Cite

The synthesis and biological activity of a series of seco-oxysterol analogs designed to be inhibitors of transcription of the gene for 3-hydroxy-3-methylglutaryl-Coenzyme A reductase (HMGR) are described. The compound possessing the most significant activity, [1 alpha (E),4 beta]-3-[2-(4- hydroxy-1-methylcyclohexyl)ethenyl]-alpha,alpha-dimethylbenzenepentan ol (4, U-88156), inhibited (IC50 = 10 microM) the expression of beta-galactosidase (beta-gal) in a transfected human HepG2 cell line wherein the beta-gal gene was driven by a 5 kB segment of the promoter for hamster HMGR. Furthermore, using wild-type HepG2 cells, it was shown that 10 microM 4 reduced HMGR mRNA levels by 73% while stimulating LDL-receptor activity by 47%. In the same system, the related oxysterol, 25-hydroxycholesterol (1), at 10 microM lowered both HMGR mRNA levels and LDL-receptor activity by 58% and 64%, respectively. Overall HMGR activity in wild-type HepG2 cells was inhibited 30% by 4 at 10 microM. These findings collectively demonstrate that a seco-oxysterol analog is capable of regulating HMGR gene expression and that this regulation can occur without a concomitant attenuation of the level of LDL-receptor activity.

show abstract

“…Chiral HPLC analyses were performed with Merck-Hitachi sys- The following substrates were purchased from commercial sources: 1-octene (Acros, distilled prior to use), 4-vinyl-1-cyclohexene (Acros), 5-hexen-1-ol (Merck), 5-hexen-2-one (AlfaAesar), 3,3-dimethyl-1-butene (AlfaAesar), 1,7-octadiene (Acros), ethyl glyoxylate (Aldrich), benzyl carbamate (AlfaAesar), and K 2 HPO 4 (Riedel-de-Haën). The following substrates were prepared according to literature procedures: 6-diphenylphosphanylpyridin-2(1H)one (6-DPPon), 11a tert-butyldimethylundec-10-enyloxysilane, 16 hex-5-enyl acetate, 17 hex-5-enyloxymethylbenzene, 18 2-dec-9enyl [1,3]dioxolane, 19 undec-10-enoic acid methylphenylamide, 20 hex-5-enyl benzoate, 21 tert-butyl carbamate. 22 Ethyl The analytical data correspond to those reported previously.…”

Section: Scheme 1 Design Of a Domino Hydroformylation-aminocatalytic mentioning

confidence: 99%

Tandem Regioselective Rhodium-Catalyzed Hydroformylation–Enantioselective Aminocatalytic anti-Mannich Reaction

Diezel

Breit

2014

Synthesis

View full text Add to dashboard Cite

The first tandem regioselective hydroformylation and enantioselective organocatalytic anti-Mannich reaction is reported. Starting from α-olefins, valuable functionalized amino acid derivatives were obtained in excellent yields and with high levels of diastereo-and enantioselectivities. The products represent valuable building blocks for biologically and pharmaceutically interesting targets.Functionalized α-amino acid derivatives are valuable building blocks for the synthesis of target structures of biological and medicinal interest. 1 As such, the development of methods for their preparation has drawn a lot of attention. 2-4 Among the many approaches used to achieve this goal, an elegant process is the organocatalytic Mannich reaction between enolizable aldehydes and imines. 5-7 However, enolizable aldehydes themselves are reactive substrates that may undergo side reactions such as aldol reactions and oligomerization, which can be obstructive for obtaining high yields. One strategy to avoid such undesired side reactions is to generate the aldehyde in a low stationary concentration by way of a catalytic reaction. As we have demonstrated recently, this can be efficiently achieved by generating an aldehyde in situ through the application of atom-economic hydroformylation of alkenes. By applying this strategy, we were able to develop an efficient enantioselective tandem regioselective hydroformylation and organocatalytic enantioselective aldol addition 8 as well as a tandem regioselective hydroformylation-Biginelli reaction. 9,10 We report herein on an extension of this concept with the development of the first tandem regio-, diastereo-and enantioselective hydroformylation-organocatalytic antiMannich reaction.Among the different known methods for organocatalytic Mannich reactions, we were attracted by the anti-selective Mannich methodology developed by Melchiore et al. 7 Central to this method is the generation of N-carbamatesubstituted imines in situ through base-initiated elimination of tolyl sulfinic acid from stable α-amidosulfones 2 (Scheme 1). An interesting aspect of this method is that NBoc or N-Cbz protected α-amino acids are obtained directly, which allows for follow-up peptide construction. Scheme 1 Design of a domino hydroformylation-aminocatalyticanti-Mannich reaction A crucial factor for success of the envisioned tandem hydroformylation-Mannich approach was the selection of the optimal catalyst system for the hydroformylation step. First, the catalyst has to be compatible with the substrates, reagents and the organocatalyst present at the same time. Second, it has to operate under mild conditions to allow for low reaction temperatures to ensure good enantioselectivities in the organocatalytic Mannich step. Finally the enolizable aldehyde reaction partner has to be generated through hydroformylation in high chemo-and regioselectivities.A catalyst system that has the potential to fulfill all these demands could be the self-assembling 6-diphenylphosphinopyridone/rhodium catalyst (6-DPPon see Scheme 1) de...

show abstract

Solvomercuration-demercuration. 8. Oxymercuration-demercuration of methoxy-, hydroxy-. and acetoxy-substituted alkenes

Abstract: The kinetic data are listed in Tables III-VII.Acknowledgment. We are grateful to Miss Takako Ishibashi for helpful discussions and experimental assistance.

Cited by 39 publications

References 1 publication

Hydroboration and Oxymercuration of Some 1‐Substituted Norborn‐2‐enes

Hydroboration and Oxymercuration of Some 1‐Substituted Norborn‐2‐enes

Design and Synthesis of Seco-oxysterol Analogs as Potential Inhibitors of 3-Hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) Reductase Gene Transcription

Tandem Regioselective Rhodium-Catalyzed Hydroformylation–Enantioselective Aminocatalytic anti-Mannich Reaction

Contact Info

Product

Resources

About