Displacement reaction of neopentyl-1-d tosylate without rearrangement and optical rotatory dispersion spectra of chiral compounds with four different groups of either C3.nu. or C.inf..nu. symmetry attached to a central carbon

Anderson, Peter H.; Stephenson, B.; Mosher, Harry S.

doi:10.1021/ja00817a025

Cited by 20 publications

(7 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The stereospecificity of enzymatic acetaldehyde reduction and ethanol oxidation was established (2-4) when it was discovered that reduction of acetaldehyde-1-d with NADH and yeast alcohol dehydrogenase (ADH) gave ethanol-1-d, which, upon enzymatic reoxidation, returned only acetaldehyde-1-d without loss of deuterium (Scheme I): Simon and coworkers (5) have extended this work by using purified enzyme systems to include propyl-1-d and butyl-1-d alcohols; while Mosher and coworkers (6)(7)(8) by using the actively fermenting yeast method have produced propyl-1-d, butyl-1-d, neopentyl-1-d, and benzyl-1-d alcohols. Where the same substrates have been tested in both systems, stereochemistries were identical.…”

mentioning

confidence: 99%

Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

Yuan

Stevens

Bau

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The absolute configuration of (+)-neopentyl-1-d alcohol, prepared by the reduction of 2,2-dimethylpropanal-l-d by actively fermenting yeast, has been determined to be S by neutron diffraction. The neutron study was carried out on the phthalate half ester of neopentyl-l-d alcohol, crystallized as its strychnine salt. The absolute configuration ofthe (-)-strychninium cation was first determined by an x-ray anomalous dispersion study of its iodide salt. The chiral skeleton of strychnine then served as a reference from which the absolute configuration of the -O-CHD-C(CH3)3 group of neopentyl phthalate was determined. Difference Fourier maps calculated from the neutron data showed unambiguously that the -0-CHD-C(CH3)3 groups of both independent molecules in the unit cell had the S configuration. This work proves conclusively that the yeast system reduces aldehydes by delivering hydrogen to the re face of the carbonyl group. The enzymatic reduction of an aldehyde to an alcohol is an important example of a stereospecific biological process that has been studied extensively (1). It is a prototype reaction for many biochemically significant transformations involving the coenzyme NADH. In addition, optically active deuterated alcohols of the type R-CHD-OH have been of great importance in the elucidation of the stereochemistry of displacement reactions at primary carbons (1).The stereospecificity of enzymatic acetaldehyde reduction and ethanol oxidation was established (2-4) when it was discovered that reduction of acetaldehyde-1-d with NADH and yeast alcohol dehydrogenase (ADH) gave ethanol-1-d, which, upon enzymatic reoxidation, returned only acetaldehyde-1-d without loss of deuterium (Scheme I): chemistries were identical. Although neopentyl-1-d and benzyl-1-d alcohols have not been produced by reductions using purified NADH and yeast ADH, it is firmly believed that the NADH/yeast ADH system is responsible for those reductions in the actively fermenting yeast system. The structure ofhorse liver ADH, which is closely related to yeast ADH, has been determined to 2.4-A resolution by x-ray diffraction techniques (9)(10)(11)(12)(13)(14). A model of the active site has been proposed in which the oxygen atom of the substrate binds directly to the zinc atom, which fixes the orientation of the substrate with respect to the coenzyme and controls the stereospecificity of the reaction (14). In this mechanism, direct hydrogen transfer from NADH to substrate is believed to take place.For the most part, the absolute configurations of deuterated alcohols (R-CHD-OH) have been determined by comparison ofNMR and polarimetry data with related molecules ofknown stereochemistry (15, 16). For example, the absolute configuration of ethanol-1-d has been deduced by correlation with a pyranose sugar whose configuration at the CHD center was established by NMR (17) and by correlation with 2-butanol-2-d (18) and pentane-2-d (19) of known configuration. In addition, the absolute configuration of glycolic-d acid, determined by neutron diffrac...

show abstract

mentioning

confidence: 99%

Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

Yuan

Stevens

Bau

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…A THF solution (800 ml, ca 0.2 N) of the di-Grignard reagent from cis-l,2-bis(2-chloroethyl)cyclohexane (16.7 g, 0.08 mol) was added in drops to 160 ml of a chilled (ice bath) THF solution of Ag0S02CF3 (45.2 g, 0.18 mol), which was vigorously stirred under Concentrations are estimated based on the quantity of alkyl halide used in preparing the di-Grignard reagent, the volume of the reaction solution containing the disilver reagent, and the assumption that the overall conversion of alkane dihalide to alkanedisilver reagent occurred in 90% yield. 6 Yields not in parentheses are GLC yields; yields in parentheses are isolated yields. Both are based on starting alkyl halide.…”

Section: Resultsmentioning

confidence: 99%

Reaction of .alpha.,.omega.-di-Grignard reagents with silver(I) salts forms carbocyclic rings

Whitesides¹,

Gutowski²

1976

J. Org. Chem.

View full text Add to dashboard Cite

“…Here, we report that under the conditions of ruthenium catalyzed transfer hydrogenation, direct tert -prenylation of isatin occurs in the absence of N -protecting groups. Furthermore, the resulting adduct, 3-hydroxy-3- tert -prenyl-oxindole 2 , is readily converted to the chloride 3 , which engages in tertiary neopentyl substitution with C -nucleophiles to furnish adducts possessing two contiguous all-carbon quaternary centers, presumably by way of an aza- o -xylylene intermediate. , To our knowledge, these studies represent the first general protocol for intermolecular substitution in a tertiary neopentyl system. , …”

mentioning

confidence: 89%

Protecting-Group-Free Synthesis of 3-tert-Prenylated Oxindoles: Contiguous All-Carbon Quaternary Centers via Tertiary Neopentyl Substitution

Grant

Krische

2009

Org. Lett.

View full text Add to dashboard Cite

Ruthenium catalyzed tert-prenylation of isatin 1 occurs efficiently in the absence of N-protecting groups under the conditions of C-C bond forming transfer hydrogenation employing 1,1-dimethylallene as the prenyl donor. The prenylated adduct, 3-hydroxy-3-tert-prenyl-oxindole 2, is converted to the tertiary neopentyl chloride 3, which participates in nucleophilic substitution by way of an aza-ortho-xylylene intermediate to furnish adducts 4a-4i. Through tertiary neopentyl substitution, two contiguous all carbon quaternary centers are established.Prenylated indole alkaloids have attracted attention due to their remarkable biological effects and challenging structural features. 1 Those incorporating tert-prenyl moieties at the 2-or 3-position include the brevianamides, austamides, paraherquamides, marcfortines, echinulins, aspergamides, norgeamides, avrainvillamides, stephacidins, notamides, roquefortines, as well as the amauromine, ardeemin, and flustramine families of natural products. The construction of indole alkaloids that incorporate a 3-tert-prenyl moiety requires construction of two contiguous all-carbon quaternary centers. Typically, this substructure is installed through the reaction of bis-N-protected tryptophan derivatives with N-(phenylseleno)phthalimide to form 3-phenylselenio-pyrroloindoline adducts, which are ionized with methyl triflate in the presence of prenyl tributylstannane. 2 Considerable pre-activation attends this method, which requires stoichiometric use of both tin and selenium reagents, as well as protection of the indolic nitrogen.In the course of studies aimed at the development of C-C bond forming hydrogenations beyond hydroformylation, 3 we recently developed a suite of catalytic methods for carbonyl allylation, 4 b,d,e,f,i,j,k crotylation 4b,c,g,k and reverse prenylation 4a,b,h,k in the absence of stoichiometric mkrische@mail.utexas.edu. Supporting Information Available. Spectral data for all new compounds ( 1 H NMR, 13 C NMR, IR, HRMS). Single crystal X-ray diffraction data for 4e. This material is available free of charge via the internet at http://pubs.acs.org. NIH Public Access Author ManuscriptOrg Lett. Author manuscript; available in PMC 2010 October 15. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript allylmetal reagents. In the specific case of reverse prenylation, 4a,b,h,k it was found that reductive C-C bond formation is achieved simply upon hydrogenation 4a or transfer hydrogenation 4b,h,k of 1,1-dimethylallene in the presence of carbonyl partners, including isatins. 4a,k Although the synthesis of 3-tert-prenylated oxindoles can be achieved through the addition of n-prenylindium reagents to isatins 5 or through enolate-Claisen rearrangement, 6 N-protected isatins are generally required. 7,8eHere, we report that under the mild conditions of transfer hydrogenation, direct tert-prenylation of isatin occurs in the absence of N-protecting groups. Furthermore, the resulting adduct, 3-hydroxy-3-tert-prenyl-oxindole 2, is readily converted to th...

show abstract

Displacement reaction of neopentyl-1-d tosylate without rearrangement and optical rotatory dispersion spectra of chiral compounds with four different groups of either C3.nu. or C.inf..nu. symmetry attached to a central carbon

Cited by 20 publications

References 6 publications

Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

Reaction of .alpha.,.omega.-di-Grignard reagents with silver(I) salts forms carbocyclic rings

Protecting-Group-Free Synthesis of 3-tert-Prenylated Oxindoles: Contiguous All-Carbon Quaternary Centers via Tertiary Neopentyl Substitution

Contact Info

Product

Resources

About