Nucleosteroids: Reaction of activated purine bases with steroidal reactive centers

Cadenas, Raúl A.; Mosettig, Jorge; Gelpi, María E.

doi:10.1016/s0039-128x(96)00199-7

Cited by 10 publications

(3 citation statements)

References 19 publications

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“…This reaction also takes place in aqueous acetic acid at 25°C, but the reaction time is increased to four days while the yield of compounds 127 is reduced to 60% [72,73]. Anticipating the more recent data on the high biological activity of the nucleosides of 6-methyl-, 6-benzyl-, or 6-(4-nitrobenzyl)thiopurines [80][81][82][83][84][85][86][87], the authors of [74,75] kept the substituents at the sulfur atom at position 6 (6-SMe, 6-SCH 2 Ph). The substituents at position 9 of the purine ring were changed, and here 6-benzylthio-9-acetylamino acids 128 (yields 62-75%) and 6-methylthio-9-β-propionic acid 129 (yields 74-87%) were obtained [75].…”

Section: -Alkyl(aralkyl)thio Protectionmentioning

confidence: 99%

The use of protecting groups in the synthesis of purine derivatives (review)

Александрова

Кочергин²

2009

Chem Heterocycl Comp

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During the synthesis of derivatives of purine from amino-, hydroxy-, thio-, or chloropurines there is often a need at position 2, 6, 7, or 9 of the purine ring to insert a protecting group that can be removed after the necessary chemical operations and retained or replaced by another pharmacophoric group during the search for biologically active substances. ALKYL (ARALKYL) PROTECTION OF POSITION 7(9)The following basic rules were established on the basis of experimental data from a large number of papers and patents relating to the nucleophilic substitution of chloropurines, reported in the monographs [1, 2]: In the series of chloro-, dichloro-, and trichloropurines the most reactive is the chlorine atom at position 6, in second place is the chlorine atom at position 8, and in third place the chlorine atom at position 2 of the purine bicycle. This rule persists in the series of 7(9)-alkyl-2,6-, -2,8-, and -6,8-dichloropurines.In the series of 7(9)-alkyl-2,6,8-trichloropurines the order of nucleophilic substitution of the chlorine atoms changes. In these compounds, unlike 2,6,8-trichloropurine, the most vulnerable center for nucleophilic attack is the chlorine atom at position 8 and then the chlorine atom at position 6 of the purine ring. The chlorine atom at position 2 was and remains the most inert in the series of 7(9)-alkyl-2,6,8-trichloropurines.In the synthesis of 8-substituted purines from 2,6,8-trichloro-7-methylpurine (1) the founder of purine chemistry E. Fischer used the methyl group as protection. Thus, 2,6-dichloro-7-methylpurin-8-one (2) was obtained by the reaction of the trichloride 1 with KOH in aqueous solution at 20°C [3].

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Section: -Alkyl(aralkyl)thio Protectionmentioning

confidence: 99%

The use of protecting groups in the synthesis of purine derivatives (review)

Александрова

Кочергин²

2009

Chem Heterocycl Comp

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“…The coupling of purine bases to the carbonyl group at C-20 of the pregnanes has been reported. 238 Steroidal selena-, tellura-and thialactones in the estrane series have been prepared. 239 A review of steroidal oxazoles, oxazolines and oxazolidinones has appeared.…”

Section: Heterocyclic Steroidsmentioning

confidence: 99%

Steroids: reactions and partial synthesis

Hanson¹

1998

Nat. Prod. Rep.

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“…We already investigated the synthesis of several steroidpurine coupling products [5,6] through an approach based on nucleophilic reactions, as was previously described by van Lier et al [7]. To broaden the range of steroids potentially useful as starting materials for coupling with nitrogenated bases, we studied the feasibility of the conditions of the Mitsunobu reaction applied to the particular case of cholesterol.…”

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confidence: 99%

Nucleosteroids: Synthesis of purinyl-steroid derivatives under mitsunobu reaction conditions

Cadenas

Gelpi

Mosettig

2005

Journal of Heterocyclic Chemistry

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The feasibility of using the Mitsunobu reaction for coupling of purines with steroids to obtain nucleosteroids was investigated in the particular case of 6‐chloropurine and cholesterol. Three principal products were obtained: 3βbT‐(6‐chloropurin‐9‐yl)‐5‐cholestene (1), 3α‐(6‐chloropurin‐9‐yl)‐5‐cholestene (2), and 6βbT‐(6‐chloropurin‐9‐yl)‐3,5‐cyclocholestane (3), isolated with 10.5%, 22.7%, and 12.6% yield, respectively. The stereochemical and structural diversity of the coupling products are explained by the formation of a homoallylic carbocation through participation of the double bond of cholesterol.

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Nucleosteroids: Reaction of activated purine bases with steroidal reactive centers

Cited by 10 publications

References 19 publications

The use of protecting groups in the synthesis of purine derivatives (review)

The use of protecting groups in the synthesis of purine derivatives (review)

Steroids: reactions and partial synthesis

Nucleosteroids: Synthesis of purinyl-steroid derivatives under mitsunobu reaction conditions

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