A fast procedure for the reduction of azides and nitro compounds based on the reducing ability of Sn(SR)3-species

Bartra, M.; Romea, Pedro; Urpı́, Fèlix; Vilarrasa, Jaume

doi:10.1016/s0040-4020(01)85439-9

Cited by 198 publications

(117 citation statements)

References 38 publications

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“…This chemistry is analogous to that previously described for the corresponding benzyl derivatives of compound 8 [12]. The pyrrolopyrimidine 9 was precipitated along with inorganic compounds after acidification, but was poorly soluble in most solvents which complicated its purification.…”

Section: Resultssupporting

confidence: 52%

Synthesis of Tricyclic Nucleoside Analogue of O6-Methyl-2'-Deoxyguanosine

Abdu¹,

Williams²

2013

IJCEA

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Section: Resultssupporting

confidence: 52%

Synthesis of Tricyclic Nucleoside Analogue of O6-Methyl-2'-Deoxyguanosine

Abdu¹,

Williams²

2013

IJCEA

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“…It was originally supposed that a key intermediate in this conversion is the hydroxylamine 4 [9], which under acid conditions forms a nitrenium cation or its equivalent with subsequent oxidative furan ring opening (scheme 4). It appears, however, that the authentic hydroxylamine 4, obtained from the nitrocompound 1a by Zn reduction in the presence of NH 4 Cl or complex Sn thiophenolates [10], does not form the ketone 3 under acid conditions. On the other hand, we have established, that the purification of the hydroxylamine 4 by column chromatography and storage at room temperature gave compound 5, contaminated with a small quantity of ketone 3.…”

Section: Resultsmentioning

confidence: 99%

o-Nitroaryl-bis(5-methylfur-2-yl)methanes as Versatile Synthons for the Synthesis of Nitrogen-Containing Heterocycles

et al. 1997

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2-Nitroaryldifurylmethanes 1a and 1b, readily available by condensation of 2-nitrobenzaldehyde and 6-nitroveratraldehyde with 2-methylfuran, were transformed into indole, cinnoline and benzothiazine-3,1 derivatives. The reduction of 2-nitroaryldifurylmethanes gave the corresponding anilines 2a,b or indole 3 depending on the reaction conditions. A plausible mechanism for the last reaction involving intramolecular heterocyclic addition between a nitroso-group and a furan ring is proposed. Diazotisation of the amine 2b gave a cinnoline derivative − a product of intramolecular oxidative furan ring opening. Treatment of isothiocyanates 7a,b with perchloric acid resulted in a new rearrangement with furan ring migration leading to the 4-Hbenzothiazine-3,1 derivatives.

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“…Exposure of the azide to Me 3 P or Ph 3 P in THF followed by the addition of water did not afford the primary amine; only decomposition of 36 was observed (69)(70)(71). Fortunately, reduction of the azide could be accomplished with SnCl 2 in the presence of PhSH and Et 3 N (72,73). This reduction protocol gave the amine in 92% yield.…”

Section: Synthesis Of Glycosyl Donor 30mentioning

confidence: 99%

Total synthesis of (–)-spinosyn A

Mergott

Frank

Roush

2004

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

127

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A convergent, highly stereoselective total synthesis of (؊)-spinosyn A (1) is described. Key features of the synthesis include the transannular Diels-Alder reaction of macrocyclic pentaene 11 and the transannular Morita-Baylis-Hillman cyclization of 12 that generates tetracycle 26. The total synthesis of (؊)-spinosyn A was completed by a sequence involving the highly ␤-selective glycosidation reaction of 13 and glycosyl imidate 30.T he spinosyns are a family of polyketide natural products that possess extraordinary insecticidal activity. The biosynthetic mixture, generated by Saccharopolyspora spinosa, comprises mostly spinosyn A (1) (Scheme 1) (Ϸ85%) and spinosyn D (Ϸ10-15%) (1-8). This mixture is currently marketed for use as an insecticide against a variety of insects (6). Total syntheses of spinosyn A have been reported by Evans and Black (9) and Paquette et al. (10,11). Synthetic StrategyDiels-Alder reactions have been proposed as key steps in the biogenesis of several natural products, including lovastatin, solanapyrone, nargenicin, and ikarugamycin (12). Kirst et al. (3) suggested that the biosynthesis of spinosyn A may involve a transannular Diels-Alder (TDA) (13) reaction of a macrocyclic pentaene to form the C(4)OC(12) and C(7)OC (11) bonds (see 4 3 3; Scheme 1). Kirst also suggested that a transannular cyclization of a 1,3-dicarbonyl nucleophile may generate the C(3)OC (14) bond (3). Alternatively, we speculated that the C(3)OC(14) bond may be formed by a vinylogous Morita-Baylis-Hillman (MBH) reaction mediated by an enzymatic nucleophile (compare 3 3 1; Scheme 1). Based on these biosynthetic considerations, we sought to assemble spinosyn A (1) via a TDA and MBH cyclization sequence of an appropriately functionalized macrocyclic pentaene 4.Diastereoselectivity of the Diels-Alder Reaction. Paramount to the success of this synthetic strategy is the control of the diastereoselectivity of the TDA reaction (4 3 3). It is known from the work of Evans and Black (9) that the intrinsic diastereofacial selectivity of the intramolecular Diels-Alder (IMDA) reaction of 5a favors the incorrect C(7)OC(11) trans-fused diastereomer 6a with 6:1 selectivity (Scheme 2). Although Evans and Black (9) addressed this issue by incorporating a chiral auxiliary (13) in the dienophile (see 5b 3 7b), we would not have recourse to this strategy for the TDA cyclization of 4. Thus, some means for controlling the stereochemistry at the C(7)OC(11) ring fusion relative to the C(9)Oalkoxy substituent in the Diels-Alder reaction was required.We initially hoped to use the steric directing-group strategy to control the diastereoselectivity of the Diels-Alder reaction (15-17), which could involve appending a bromine steric directing group at C(6) of the IMDA or TDA substrate to control the stereochemical outcome of the cycloaddition, leading to the desired C(7)OC(11) trans-fused diastereomer. It was anticipated that TS2, which leads to the undesired C(7)OC(11) trans-fused isomer 10 and is favored in the absence of the C(6)OBr steric direct...

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A fast procedure for the reduction of azides and nitro compounds based on the reducing ability of Sn(SR)3-species

Cited by 198 publications

References 38 publications

Synthesis of Tricyclic Nucleoside Analogue of O6-Methyl-2'-Deoxyguanosine

Synthesis of Tricyclic Nucleoside Analogue of O6-Methyl-2'-Deoxyguanosine

o-Nitroaryl-bis(5-methylfur-2-yl)methanes as Versatile Synthons for the Synthesis of Nitrogen-Containing Heterocycles

Total synthesis of (–)-spinosyn A

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