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1.
J Am Chem Soc ; 146(26): 17757-17764, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38885121

ABSTRACT

The sealutomicins are a family of anthraquinone antibiotics featuring an enediyne (sealutomicin A) or Bergman-cyclized aromatic ring (sealutomicins B-D). Herein we report the development of an enantioselective organocatalytic method for the synthesis of dihydroquinolines and the use of the developed method in the total synthesis of sealutomicin C which features a transannular cyclization of an aryllithium onto a γ-lactone as a second key step.

2.
Org Lett ; 19(8): 2050-2053, 2017 04 21.
Article in English | MEDLINE | ID: mdl-28375019

ABSTRACT

Electrochemical deprotection of p-methoxybenzyl (PMB) ethers was performed in an undivided electrochemical flow reactor in MeOH solution, leading to the unmasked alcohol and p-methoxybenzaldehyde dimethyl acetal as a byproduct. The electrochemical method removes the need for chemical oxidants, and added electrolyte (BF4NEt4) can be recovered and reused. The method was applied to 17 substrates with high conversions in a single pass, yields up to 92%, and up to 7.5 g h-1 productivity. The PMB protecting group was also selectively removed in the presence of some other common alcohol protecting groups.

3.
J Org Chem ; 79(22): 10932-44, 2014 Nov 21.
Article in English | MEDLINE | ID: mdl-25337869

ABSTRACT

A range of enantiopure polyhydroxylated piperidines, including (2R,3S,4R)-dihydroxypipecolic acid, (-)-3-epi-fagomine, (2S,3S,4R)-dihydroxyhomopipecolic acid, (2S,3R,4R)-dihydroxyhomopipecolic acid, and two trihydroxy-substituted homopipecolic acids, have been prepared using diastereoselective olefinic oxidations of a range of enantiopure tetrahydropyridines as the key step. The requisite substrates were readily prepared from tert-butyl sorbate using our diastereoselective hydroamination or aminohydroxylation protocols followed by ring-closing metathesis. After diastereoselective olefinic oxidation of the resultant enantiopure tetrahydropyridines and deprotection, enantiopure polyhydroxylated piperidines were isolated as single diastereoisomers (>99:1 dr) in good overall yield.


Subject(s)
Imino Pyranoses/chemical synthesis , Pipecolic Acids/chemistry , Piperidines/chemistry , Imino Pyranoses/chemistry , Molecular Structure , Oxidation-Reduction , Stereoisomerism
4.
J Am Chem Soc ; 128(8): 2514-5, 2006 Mar 01.
Article in English | MEDLINE | ID: mdl-16492017

ABSTRACT

The use of N-sulfonyloxy carbamates as reoxidants for the tethered aminohydroxylation (TA) reaction is reported. These new conditions obviate the requirement for lithium hydroxide and tBuOCl in the oxidation mixture. In addition to providing aminohydroxylation products in good yields, the catalyst loadings can be reduced to just 1 mol % osmium. Moreover, for the first time, homoallylic alcohols are now viable substrates for the TA reaction.


Subject(s)
Carbamates/chemistry , Oxidants/chemistry , Sulfinic Acids/chemistry , Hydroxylation , Models, Molecular , Propanols/chemistry
5.
Org Lett ; 5(24): 4749-52, 2003 Nov 27.
Article in English | MEDLINE | ID: mdl-14627431

ABSTRACT

[reaction: see text] The palladium-catalyzed coupling of a range of enol triflates with amides, carbamates, and sulfonamides has been developed. This offers a simple and widely applicable synthesis of enamides, which may not be readily available by other means.

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