Stereoselective Synthesis of 3-Hydroxy-2-aryltetrahydrofurans from β-(Triethylsilyl)oxyaldehydes and Aryldiazomethanes

Angle, Steven R.; Neitzel, Martin L.

doi:10.1021/jo991362w

Cited by 10 publications

(3 citation statements)

References 11 publications

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“…If this were the case, it seemed likely that methanol, or other alcohols, might serve a dual role as solvent for aryldiazomethane synthesis and promoter for the addition of the diazo compound to the aldehyde. In an effort to test this notion, aldehyde 3 was treated with phenyldiazomethane (2 equiv) in methanol (rt, 2 days) to afford benzyl ketone 4 in 78% yield after flash chromatography (eq 2). This result provides an opportunity for realizing a one-pot aldehyde to ketone homologation reaction.…”

Section: Resultsmentioning

confidence: 99%

A Simple Method for the Synthesis of Substituted Benzylic Ketones: Homologation of Aldehydes via the in Situ Generation of Aryldiazomethanes from Aromatic Aldehydes

Angle

Neitzel

2000

J. Org. Chem.

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A general method for the homologation of aldehydes to benzylic ketones has been developed. Aryldiazomethanes were generated in situ in the presence of an aldehyde by simply heating the tosylhydrazones of aromatic aldehydes in the presence of a stoichiometric amount of base in polar protic solvents. The resulting polar protic solvent promoted homologation afforded benzylic ketones in moderate to excellent yields with a variety of aldehydes. Isolation of the tosylhydrazones was not necessary; they could be prepared in ethanol and carried through the sequence without isolation. This methodology allows easy access to a wide variety of substituted aryldiazomethanes that would be difficult, or even impossible, to prepare via conventional methods and circumvents the toxicity and stability problems associated with the isolation and/or handling solutions of aryldiazomethanes.

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Section: Resultsmentioning

confidence: 99%

A Simple Method for the Synthesis of Substituted Benzylic Ketones: Homologation of Aldehydes via the in Situ Generation of Aryldiazomethanes from Aromatic Aldehydes

Angle

Neitzel

2000

J. Org. Chem.

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“…新制 20 mmol/L 乙醇钠-乙醇溶液; 将得到的中间体 2 每个分成三等份(附上标签 1a_3a, 1a_3b [11] , 1a_3c, 1b_3a, 1b_3b [11] , 1b_3c, 1c_3a, 1c_3b, 1c_3c, 1d_3a, …”

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A New Synthesis of 2-Amino-4,5-substituted Pyrimidine Derivatives

邓兰青¹,

徐中海²,

尚云峰³

et al. 2012

Chin. J. Org. Chem.

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In this paper, a novel synthetic method for 2-amino-4,5-substituted pyrimidine derivatives was reported, which began from cheap and simple four aromatic aldehydes and three aliphatic aldehydes. 12 compounds of 2-amino-4,5-substituted pyrimidine derivatives were synthesized by four steps with yields of 40%～70%. The structures of terminational compounds were determined by 1 H NMR, 13 C NMR and LC-MS techniques.

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“…Cyclic hemiacetal 5, derived from commercially available (R)-pantolactone (>98% ee) in two steps, was subjected to the same conditions mentioned above to obtain the phenyl-migration product 6 in moderate yield with >95% cis at the C1-C2 relationship and 93% dr at the silicon stereocenter (S Si ) was yielded. Its 1,2-cis and S Si stereochemistries were established by the transformation to 7 (>95% cis) 12 or benzyloxysilanol (R)-4 (85% ee), respectively. 13 Thus, the developed phenyl migration protocol was also applicable to the six-membered cyclic acetal system (Scheme 5).…”

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confidence: 99%

Stereoselective 1,4-Phenyl Migration from Silicon to Carbon in α-Siloxy Cyclic Acetal Systems: A Concise Synthesis of 1,2-cis-Phenyl C-Glycoside and Enantioenriched Silanol

Nakazaki

Usuki

Tomooka³

2008

Synlett

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The treatment of O-glycoside with alcohol in the presence of montmorillonite K10 clay and 4-Å MS yields the 1,4-aryl migration product with a 1,2-cis-phenyl C-glycoside scaffold and a chiral silyl moiety with high stereoselectivity.Aryl C-glycosides constitute an important class of the Cglycoside family of natural products and have attracted considerable interest because of their diverse biological activities and resistance to acidic and enzymatic hydrolysis. 1 Therefore a number of methods have been developed for the stereoselective formation of the aryl C-glycoside linkage. 2 Among these methods, the reactions of glycosyl donors by intermolecular Friedel-Crafts couplings or by reactions with aryl metal reagents have been well established and these reactions yielded 1,2-trans-aryl C-glycosides, predominantly. In contrast, access to the thermodynamically more unfavorable 1,2-cis-aryl C-glycosides remains relatively undeveloped. 3 To this end, we have recently reported that montmorillonite K10 clay promoted 1,4-aryl or alkenyl migration from silicon to the C1 carbon in cyclic N,O-acetal systems. 4-6 The unique features of this reaction are as follows: (i) the aryl or alkenyl group on the siloxy group migrates intramolecularly in a cis fashion, and (ii) a concomitant nucleophilic substitution of the alkoxy group on the silicon atom proceeds with high stereoselectivity. On the basis of this result, we envisioned that a similar aryl migration of O-glycoside A with a tert-butyldiphenylsilyl group at the C2 hydroxyl group could afford the phenyl C-glycosides B in a 1,2-cis fashion (Scheme 1). Desilylation of B would provide C2 hydroxy phenyl C-glycoside C. Furthermore, the treatment of phenyl C-glycosides B with a base would cause b-elimination and provide enantioenriched silanols D, which are otherwise difficult to obtain. Here, we report the details of the aryl migration in cyclic acetal systems, which provide an effective approach to the stereoselective synthesis of 1,2-cis-phenyl C-glycosides as well as chiral silanol.At the outset, we attempted the phenyl migration of the simple five-membered cyclic hemiacetal 1a with the (tertbutyldiphenylsilyl)oxy group at the C2 position; the cyclic hemiacetal 1a was easily prepared from commercially available (S)-a-hydroxy-g-butyrolactone (97% ee) in two steps [(i) TBDPSCl, imidazole and (ii) DIBAL]. The reaction was performed according to the previously developed protocol; the cyclic hemiacetal 1a was treated with two equivalents of benzyl alcohol in the presence of K10 and 4-Å MS in CH 2 Cl 2 at 0 °C for 12 hours, providing the corresponding aryl migration product 2 in 71% yield with 90% diastereomeric ratio (Scheme 2). 7,8 Some of the aryl migration product 2 may be produced through benzyl acetal 1b; indeed a similar reaction of separately prepared 1b 9 also provided 2 in 46% yield with 90% dr.The exposure of the phenyl migration product 2 to TBAF afforded alcohol 3a as a single diastereomer, which means that the diastereomer of 2 is derived from the silicon stereocenter. T...

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Stereoselective Synthesis of 3-Hydroxy-2-aryltetrahydrofurans from β-(Triethylsilyl)oxyaldehydes and Aryldiazomethanes

Cited by 10 publications

References 11 publications

A Simple Method for the Synthesis of Substituted Benzylic Ketones: Homologation of Aldehydes via the in Situ Generation of Aryldiazomethanes from Aromatic Aldehydes

A Simple Method for the Synthesis of Substituted Benzylic Ketones: Homologation of Aldehydes via the in Situ Generation of Aryldiazomethanes from Aromatic Aldehydes

A New Synthesis of 2-Amino-4,5-substituted Pyrimidine Derivatives

Stereoselective 1,4-Phenyl Migration from Silicon to Carbon in α-Siloxy Cyclic Acetal Systems: A Concise Synthesis of 1,2-cis-Phenyl C-Glycoside and Enantioenriched Silanol

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