One-pot synthesis of N-[(trimethylsilyl)methyl]imines and (trimethylsilyl)methyl-substituted heterocumulenes from (trimethylsilyl)methyl azide

Tsuge, Otohiko; Kanemasa, Shuji; Matsuda, Koyo

doi:10.1021/jo00189a006

Cited by 59 publications

(11 citation statements)

References 3 publications

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“…As for the isothiocyanate synthesis, a convenient one-pot procedure was reported by Tsuge et al in 1984 as is to say the tandem Staudinger/azaWittig reaction.…”

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confidence: 99%

“…As for the isothiocyanate synthesis, a convenient one-pot procedure was reported by Tsuge et al in 1984 as is to say the tandem Staudinger/azaWittig reaction. 6,7) They used carbon disulfide (CS 2 ) as the co-solvent in the reaction of only (trimethylsilyl)methylazide with triphenylphosphine (PPh 3 ), 6) and the yield of the corresponding isothiocyanate was superior to that obtained from a stepwise method 8) in which CS 2 was added to the primary reaction mixture containing the azaylide product. Especially, the tandem method was recently utilized in a carbohydrate field in order to effectively obtain isothiocyanate-functionalized sugars.…”

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confidence: 99%

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Efficient Synthesis of Isothiocyanates Based on the Tandem Staudinger/aza-Wittig Reactions and Mechanistic Consideration of the Tandem Reactions

Isoda¹,

Hayashi²,

Tamai³

et al. 2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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The reaction of organic azides with trivalent phosphorous compounds to afford the corresponding azaylides is known as the Staudinger reaction.1) This reaction proceeds via a primary imination adduct, phosphazide, which spontaneously decomposes into azaylide and nitrogen in most cases.2) The azaylide product can usually be isolated as a stable compound, which can be used to prepare various amines, imines, amides, isocyanates, isothiocyanates, 3,4) and so forth, 5) as a versatile synthetic intermediate. As for the isothiocyanate synthesis, a convenient one-pot procedure was reported by Tsuge et al. in 1984 as is to say the tandem Staudinger/azaWittig reaction.6,7) They used carbon disulfide (CS 2 ) as the co-solvent in the reaction of only (trimethylsilyl)methylazide with triphenylphosphine (PPh 3 ), 6) and the yield of the corresponding isothiocyanate was superior to that obtained from a stepwise method 8) in which CS 2 was added to the primary reaction mixture containing the azaylide product. Especially, the tandem method was recently utilized in a carbohydrate field in order to effectively obtain isothiocyanate-functionalized sugars.9-11) Herein, we investigated the substrate generality of the tandem and stepwise Staudinger/aza-Wittig reactions and their reaction mechanisms utilizing a 1 H-NMR analysis. Results and DiscussionOur first target was to prepare chloroethylisothiocyanate (3a), because 3a was an indispensable material for the synthesis of 3-mercapto-1-(1,3-thiazolin-2-yl)azetidine (1), useful for the pendant moiety of the oral carbapenem antibiotic L-084 (Chart 1).12) In recent years, the development of new antibiotics has attracted the attention in the clinical realm for the treatment of severe infectious diseases. L-084 is one of several promising candidates for oral administration and is now under clinical trials. During the course of our synthetic study of L-084, we established an efficient synthetic route for 1 from 2 and 3a, 13) but to the best of our knowledge, there was no application to prepare 3a without using the harmful and toxic thiophosgene. 14,15) Thus, we planned to develop an effective and harmless synthetic route for 3a in which scaleup production would be possible. Chloroethylisothiocyanate (3a) was initially prepared from the reaction of chloroethylazide (5a) 16) and PPh 3 followed by the aza-Wittig reaction with CS 2 , but 3a was obtained in only 16% yield from 5a due to the decomposition of the unstable intermediate 8a (Entry 1 in Table 1). As a result of the optimization of the reaction conditions, we found that the yield of 3a dramatically increased to 83% when CS 2 was used as the co-solvent in the reaction of 5a with Ph 3 P, compared to the above stepwise method.At this point, we investigated in detail the tandem Staudinger/aza-Wittig reactions (Method I) and the stepwise reactions (Method II), as shown in Table 1. Namely, several azides 5b-g were treated with Ph 3 P in a mixed solvent of CS 2 and CHCl 3 to afford the corresponding isothiocyanates in good yields except for th...

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“…As for the isothiocyanate synthesis, a convenient one-pot procedure was reported by Tsuge et al in 1984 as is to say the tandem Staudinger/azaWittig reaction.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Efficient Synthesis of Isothiocyanates Based on the Tandem Staudinger/aza-Wittig Reactions and Mechanistic Consideration of the Tandem Reactions

Isoda¹,

Hayashi²,

Tamai³

et al. 2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…The reaction of trimethylsilylmethyliminotriphenylphosphorane, obtained in situ from trimethylsilylmethyl azide and triphenylphosphine, with furfural gave alter 2 h the corresponding trimethylsilylmethylimine with a 75% yield [162]. ZnCI,…”

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confidence: 99%

Furan derivatives of group IV elements (review)

Lukevits¹,

Pudova²

1995

Chem Heterocycl Compd

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“…As an example of an intermolecular aza-Wittig reaction, the one-pot reaction of (trimethylsilyl)methyl azide (72) with triphenylphosphine and an aldehyde can be put forward; [280] N-[(trimethylsilyl)methyl]imines 73 are obtained in 46-89% yield (Scheme 30).…”

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“…[300] ø-Azido carbonyl compounds may be reduced with in situ prepared iodotrimethylsilane, leading to the cyclic imines. [301] N-Benzylidene-N-[(trimethylsilyl)methyl]amine (73, R 1 = H; R 2 = Ph); Typical Procedure: [280] To a soln of Ph 3 P (2.86 g, 11.0 mmol) in dry benzene (6 mL) (CAUTION: carcinogen) was added a mixture of (trimethylsilyl)methyl azide (72; 1.42 g, 11.0 mmol) and PhCHO (1.06 g, 10.0 mmol) at rt. The mixture was refluxed under N 2 for 2 h. The solvent was removed under reduced pressure and the residue was triturated with hexane (50 mL).…”

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confidence: 99%

Product Class 7: Imines

Padwa¹,

Bellus²

2005

Category 4. Compounds With Two Carbon Heteroatom Bonds

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Compounds with the general structure R 1 R 2 C=NR 3 , referred to as imines, were first obtained by Schiff via condensation of ketones and aldehydes with primary amines. Therefore, the condensation products are also called Schiff bases. In addition, the nominations azomethine, ketimine (derived from ketones), aldimine (derived from aldehydes), and anil (derived from anilines) are in use. It is recommended that the terms imine(s), ketimine(s), or aldimine(s) are used, rather than Schiff base(s) or azomethine(s).Since imines have to be considered as analogues of carbonyl compounds, many of the chemical properties are similar to the latter. Imines are used in new C-C bond formations, and reactions with electrophiles (e.g., aldehydes, alkyl halides), and the C=N moiety can undergo nucleophilic reactions. Generally, imines are very useful compounds in organic synthesis, as they are used in several syntheses of aza-heterocyclic compounds. Most imines are stable in an alkaline medium and therefore can be dried over potassium hydroxide. In diluted acid, however, they are easily hydrolyzed. In many cases intermediary imines cannot be isolated because of their lability. The presence of a C=N bond creates the possibility for E/Z isomerism (syn/anti). It has been recognized that such geomet-

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One-pot synthesis of N-[(trimethylsilyl)methyl]imines and (trimethylsilyl)methyl-substituted heterocumulenes from (trimethylsilyl)methyl azide

Cited by 59 publications

References 3 publications

Efficient Synthesis of Isothiocyanates Based on the Tandem Staudinger/aza-Wittig Reactions and Mechanistic Consideration of the Tandem Reactions

Efficient Synthesis of Isothiocyanates Based on the Tandem Staudinger/aza-Wittig Reactions and Mechanistic Consideration of the Tandem Reactions

Furan derivatives of group IV elements (review)

Product Class 7: Imines

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