Antipodal forms of β-lactams via stereospecific reactions

Wagle, D. R.; Garai, C.; Monteleone, M. G.; Bose, Ajay K.

doi:10.1016/s0040-4039(00)82008-0

Cited by 33 publications

(7 citation statements)

References 19 publications

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“…Caled for C15H15FN20: C, 69.75; H, 5.85; N, 10.85. Found: C, 69.92; H, 5.94; N, 10.92. Preparation of 4-(4-Pyridyl)-5-(4-fluorophenyl)imidazole-2-thione (1). A solution of 6 (10.32 g, 40.0 mmol) in 100 mL of ethyl acetate was treated with 10% aqueous hydrochloric acid.…”

Section: Methodsmentioning

confidence: 99%

“…In the early stages of our studies® on /3-lactams, we achieved a completely diastereoselective synthesis of a 6-epipenicillin V methyl ester (4) by using a chiral thiazoline (2) and an achiral acid chloride (1) as the reactants (Scheme I). The stereochemistry at the ring junction carbon (C-5) in 3 is determined by the configuration of the carboxyl group bearing carbon (C-3) since the carboxyl group is sterically less hindered in the exo position.…”

mentioning

confidence: 99%

“…The diastereoselectivity varied depending on the nature of substituents on the amino compound from which the Schiff base was prepared. For instance, we8 observed the formation of two cis ßlactams (12a and 13a) in nearly 50:50 proportion by the reaction of an acid chloride (1) and triethylamine with a Schiff base (11a) from cinnamaldehyde and a D-threonine ester (Scheme III). Tenneson and Belleau9 1011used a tertbutyldimethylsilyl ether of a D-threonine ester, e.g., lib, f Dedicated to the memory of Professor James M. van der Veen.…”

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confidence: 99%

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Synthetic and mechanistic studies on the preparation of pyridyl-substituted imidazothiazoles

Lantos¹,

Gombatz²,

McGuire³

et al. 1988

J. Org. Chem.

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A new method is presented for the introduction of the 4'-pyridyl substituent into 6-aryl-2,3-dihydroimidazo[2,1-b]thiazoles. The method involves treatment of the imidazothiazolines with the reactive complex of pyridine and ethyl chloroformate and oxidative deethyl carboxylation of the dihydropyridine adducts formed. Sulfur in refluxing mesitylene was found most suitable for the latter reaction, but chromium trioxide in pyridine or KtBuO and air were also effective.Optically active 3,4-disubstituted 2-azetidinones have been prepared in good yield by the annelation of Schiff bases from D-glyceraldehyde acetonide with acid chlorides (or equivalent) and triethylamine. The utility of this enantiospecific synthesis was extended by the stereocontrolled modification of functional groups leading to optically active trans 6-lactams. The absolute configuration of some key compounds was determined by chemical degradation.Modification of substituents on the P-lactam ring led to optically active intermediates for a variety of natural products, such as alkaloids, carbohydrates, and amino acids.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

See 1 more Smart Citation

Synthetic and mechanistic studies on the preparation of pyridyl-substituted imidazothiazoles

Lantos¹,

Gombatz²,

McGuire³

et al. 1988

J. Org. Chem.

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“…It has been demonstrated that this is due to a stabilizing interaction between the enolate HOMO and C-X s* orbital which is more pronounced in one of the diastereomeric helical transition states. 85,114 The most commonly employed chiral aldehydes are derived from sugars, [115][116][117][118][119] amino acids 85 and synthetic chiral epoxyaldehydes. 120 The levels of stereocontrol can be near-perfect, as demonstrated by Deshmukh et al, who employed an isosorbide-derived aldehyde (Scheme 18).…”

Section: Thermal Reactions 4p Electrocyclizations ( P 4 a )mentioning

confidence: 99%

Asymmetric electrocyclic reactions

et al. 2011

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“…The residue was chromatographed on silica to give the title azetidin-2-one (4a) (92 mg, 59%), m.p. 94-95°C; m/z 247.1212 (M') [Calc. for Cl4HI7NO3 (M') m/z 247.12081; m/z 247 (M', 373, 232 (15), 219 (6), 204 (8), 105 (loo), and 77 (92); vmx. 1 720 and 1 740 cm-', 6 1.40 (s, 9 H, But), 2.81 (dd, J 1,14 Hz, 1 H, cis-3-H), 3.33 (dd, J4,14 Hz, 1 H, trans-3-H), 6.34 (dd, J 1,4, Hz, 1 H, 4-H), and 7.20-8.30 (m, 5 H, ArH).…”

Section: N-(4-methoxypheny1)-n"-phthaloylserinamide (2gmentioning

confidence: 99%

Acyloxylation at the 4-position of azetidin-2-ones

Easton¹,

Love²,

Wang³

1990

J. Chem. Soc., Perkin Trans. 1

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The copper-catalysed reaction of azetidin-2-ones with t-butyl perbenzoate or peracetate affords the corresponding 4-benzoyloxy-and acetoxy-substituted p-lactams, respectively. N -Unsubstituted 4acyloxyazetidinones can be synthesized by dearylation of the N-(4-methoxyphenyl) -substituted products with ceric ammonium nitrate. Acyloxylation of p-lactams that are monosubstituted at C-3 affords predominantly trans-products.4-Acetoxy-and benzoyloxy-substituted azetidin-2-ones have been used extensively in organic synthesis, particularly as precursors of p-lactam antibiotics.Consequently, there is considerable interest in the development of methods for the synthesis of compounds of this type. Here7 we describe a method for the synthesis of 4-acyloxy-substituted azetidinones through the copper-catalysed reaction of p-lactams with t-butyl peresters.The only alternative procedure that has been reported for the direct acyloxylation of p-lactams at the 4-position involves the electrochemical oxidation of azetidin-2-ones in acetic acidacetonitrile.* This latter method is an extension of previous work on the introduction of alkoxy substituents through electrolysis of P-lactam~.~*'~ It has also been reported that oxidation of N-hydroxyazetidines with lead tetra-acetate gives the corresponding 1,4-diacetoxyazetidinones, but this process is thought to occur by 1,4-addition of the oxidizing agent to intermediate nitrones, not by direct substitution of p-lactams.'

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Antipodal forms of β-lactams via stereospecific reactions

Cited by 33 publications

References 19 publications

Synthetic and mechanistic studies on the preparation of pyridyl-substituted imidazothiazoles

Synthetic and mechanistic studies on the preparation of pyridyl-substituted imidazothiazoles

Asymmetric electrocyclic reactions

Acyloxylation at the 4-position of azetidin-2-ones

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