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Biomedical subjects

B M Trost

Publications and source records attributed to B M Trost.

36 records · Page 2Linked to original sources
PubMed2000

Asymmetric synthesis of quaternary centers. Total synthesis of (-)-malyngolide.

[structure] The deracemization of 3-nonyl-3,4-epoxybut-1-ene with Pd(0) in the presence of chiral ligands using p-methoxybenzyl alcohol as a nucleophile proceeds regio- and enantioselectively to form the monoprotected vinylglycidol in 99% ee. This chiral building block was converted in seven steps to (-)-malyngolide, an antibiotic showing significant activity against Mycobacterium smegmatis and Streptococcus pyogenes. An interesting aspect involves controlling the diastereoselectivity of protonation of an enolate via a distal hydroxyl group.

Alkylation↗
PubMed2000

On the regioselectivity of the Ru-catalyzed intramolecular [5 + 2] cycloaddition.

The influence of substituents on which cyclopropyl bond cleaves in the cycloisomerization of cyclopropylenynes catalyzed by CpRu(N&tbd1;CCH(3))(3)(+)PF(6)(-) is compared to the corresponding Rh-catalyzed reaction. With the trans cyclopropyl substrates, the bond energy of the cleaving bond appears to be an important factor. With cis cyclopropyl substrates, steric effects appear to dominate.

Alkenes↗
PubMed2000

A regioselective Ru-catalyzed alkene-alkyne coupling.

[reaction: see text] The reaction of silylalkynes and terminal alkenes proceeds with complete control of regioselectivity by the silyl substituent to give geometrically defined vinylsilanes. Since terminal alkynes normally give mixtures, protodesilylation of these adducts then constitutes a regioselective addition of terminal alkynes to terminal alkenes.

Alkenes↗
PubMed2000

A new strategy for cyclopentenone synthesis.

[reaction--see text] A new strategy for the synthesis of 2,3-disubstituted cyclopentenones emerges from two key reactions-the ruthenium-catalyzed three-component coupling of an equivalent of HBr, an alkyne, and a vinyl ketone and the Ni-Cr Barbier type reaction. As a result, these important structures are readily accessed from an alkyne and a vinyl ketone (which derive directly from carboxylic acids). Syntheses of tetrahydrodicranenone B and rosaprostol illustrate the new strategy.

Anti-Infective Agents↗
PubMed1999

On the synthesis of Z-gamma-amino-alpha,beta-unsaturated esters via Ru-catalyzed coupling.

[formula: see text] A synthesis of gamma-amino acids and their cyclic derivatives, 3-pyrrolinones, from alpha-amino acids employs a ruthenium-catalyzed Alder ene reaction as a key step in the sequence. Cyclopentadienylruthenium (1,4-cyclooctadiene) chloride catalyzes the addition of gamma-amido-alpha,beta-alkynoate esters with monosubstituted alkenes. The major product arises from C-C bond formation at the alpha-carbon of the alkynoate. The reaction exhibits high chemoselectivity. The ruthenium-catalyzed addition occurs in preference to a Diels-Alder reaction. The two new double bonds are created with complete geometrical control. The initial gamma-amido-alpha,beta-unsaturated ester can be cyclized to the pyrrolinones with a tin catalyst.

Alkenes↗
PubMed1991

The atom economy--a search for synthetic efficiency.

Efficient synthetic methods required to assemble complex molecular arrays include reactions that are both selective (chemo-, regio-, diastereo-, and enantio-) and economical in atom count (maximum number of atoms of reactants appearing in the products). Methods that involve simply combining two or more building blocks with any other reactant needed only catalytically constitute the highest degree of atom economy. Transition metal-catalyzed methods that are both selective and economical for formation of cyclic structures, of great interest for biological purposes, represent an important starting point for this long-term goal. The limited availability of raw materials, combined with environmental concerns, require the highlighting of these goals.

Chemical Phenomena↗
PubMed1990

An asymmetric approach to 2-deoxynucleosides via organosulfur building blocks as chemical chameleons.

An asymmetric synthesis of 6-N-benzoyl-5'-O-benzyl-2'-deoxyadenosine and its a anomer from non-carbohydrate building blocks is achieved in 7 steps. The sequence builds the basic structures using bis(methylthio)methane and methylthiomethyl phenyl sulfone as both nucleophilic and electrophilic building blocks, a feature that suggests their behavior as chemical chameleons. The asymmetric induction is achieved utilizing a kinetic resolution based upon catalytic asymmetric epoxidation.

Chemical Phenomena↗
PubMed1985

Sculpting horizons in organic chemistry.

Organic chemistry as a discipline derives from and impacts on the biological and abiological world in which we live. Its challenges lie in the areas of structure, reactivity, techniques, and concepts. Powerful structural tools reveal structures from biology that range from control of insect development and behavior to whole new metabolic pathways in humans. Unnatural products create beautiful new molecular shapes whose properties cannot be predicted as well as catalysts that function with enzyme-like control. From structure flows reactivity. Exploration of known reactions points to new directions, and development of new reactions offers the opportunity of streamlined synthetic design. Emerging new techniques offer new dimensions for performing and studying reactions as well as the hope for developing new ones. Merging disparate facts into unified concepts increases predictive capabilities. The extraordinary difficulty of finding the resultant of many small effects may obscure the presence of general theories, creates the art in the practice of the science, and challenges the practitioner. From these general themes derives the quest for selectivity--chemo-, regio-, diastereo-, and enantio-. An examination of the fundamental underpinnings of the applications of organic chemistry reveals that, while impressive strides have been made, the science is best described as being between infancy and childhood. The cross-fertilization between organic chemistry and molecular biology vividly illustrates a merging of chemistry and biology.

Alkylation↗
PubMed1983

Leucinopine, a characteristic compound of some crown-gall tumors.

An unusual compound has been found in crowngall tumors induced by those Agrobacterium tumefaciens strains that utilize neither octopine nor nopaline. The compound has been isolated and shown by proton and carbon-13 NMR spectroscopy and by synthesis to be N(2)-(1,3-dicarboxypropyl)-L-leucine, which also exists in a cyclized (i.e., lactam) form. This compound, which we name "leucinopine," was not detected in octopine tumors, nopaline tumors, or the tumors induced by A. tumefaciens strains 181 and EU6.

Journal Article↗