EFFICIENT PREPARATION OF THE CHIRAL AUXILIARIESSAMPandRAMP.N-AMINATIONviaHOFMANN DEGRADATION

Enders, Dieter; Fey, Peter; Kipphardt, Helmut

doi:10.1080/00304948509355464

Cited by 40 publications

(10 citation statements)

References 13 publications

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“…In addition to the expected carbon-carbon bond formation, hydrolysis of the methyl ester also occurred. 20 Both 31P and *H NMR spectroscopy showed the product to be a mixture of diastereomers, epimeric at C-2 (2R:2S = 1.5:1.0). 21,22 The sodium salt of 4 was reduced by using a variety of reagents and conditions (eq 3; Table I anti disastereomer was required, we focused our attention on the use of the triacetoxyborohydrides.23 Although the diastereoselectivities were lower than had previously been observed23,24 (possibly due to the influence of the neighboring phosphate group), both sodium and tetramethylammonium triacetoxyborohydride gave the desired anti configuration as the dominant isomer (anti:syn = 4:1).25 No attempt was made to separate these (17) Bischofberger, N.; Whitesides, G. M. Unpublished results.…”

Section: Resultsmentioning

confidence: 99%

A combined chemical-enzymic synthesis of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate

Turner¹,

Whitesides²

1989

J. Am. Chem. Soc.

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Section: Resultsmentioning

confidence: 99%

A combined chemical-enzymic synthesis of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate

Turner¹,

Whitesides²

1989

J. Am. Chem. Soc.

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“…The selectivity of the nucleophilic substitution at the 3-position of the cyclobutenylidene ring was investigated by use of the difunctional aminothiole cysteine (15). Even at −40°C the complexes 3a -c react in methanol with 15 within a few seconds to give the 3-aminocyclobutenylidene complexes 16a -c in 70 -86% yield.…”

Section: Resultsmentioning

confidence: 99%

“…Elemental analyses: Heraeus CHN-O-RAPID. The vinylidene complexes 1a [10], 1b [1], 1c [9], the 3-ethoxy-cyclobut-2-en-1-ylidene complexes 3a [3], the alkyne 2 [13] and the amines (R)-5 [14] and (S)-7 [15] were prepared according to literature procedures. All other compounds were commercially available and were used without further purification.…”

Section: Generalmentioning

confidence: 99%

Aminolysis of 3-alkoxysubstituted cyclobutenylidene complexes. A novel convenient route to chiral 3-aminosubstituted cyclobutenylidene complexes

Karl¹,

Joneleit²,

Weißenbach³

et al. 2001

Journal of Organometallic Chemistry

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Aminolysis of 3-alkoxycyclobutenylidene complexes offers a convienient and high-yield route to a variety of 3-aminocyclobutenylidene complexes. Thus, the 3-diethylaminocyclobutenylidene complexes [(CO) 5 Cr C(C(Me) C(NEt 2) Ç ¹¹¹¹¹¹¹¹¹¹¹º R 2)] [(4), R 2 (CH 2) 5 (a), Me 2 (b), Ph 2 (c)] are obtained by substitution of NEt 2 of diethylamine for the ethoxy group in [(CO) 5 Cr C(C(Me)C(OEt) Ç ¹¹¹¹¹¹¹¹¹º R 2)] (3a-c). The reactions of (R) N-methyl-1-phenylethyl amine and of (S)-2-methoxymethylpyrrolidine with 3a-c afford the 3-N-methyl-(1-phenylethyl)amino-and 3-(2-methoxymethyl-pyrrolidino)-substituted cyclobutenylidene complexes, respectively, as mixtures of the E and Z isomers (with respect to the C3 N bond). Mixtures of the E and Z isomers of 3-(amino acid ester)-substituted cyclobutenylidene complexes are obtained from 3a,b and the methylester of L-leucine, L-phenylalanine, and L-methionine in yields ranging from 82 to 94%. The E/Z ratio strongly depends on the amino acid and the substituents at the sp 3-C atom of the cyclobutenylidene ring. The reactions of 3a-c with cysteine, H 2 N C 2 H 4 SH, proceed highly selectively. Only 3-aminocyclobutenylidene complexes are isolated in 73-86% yield. The formation of 3-organylthiocyclobutenylidene complexes has not been detected. The structure of the E-leucinyl methylester-substituted complex has been established by an X-ray structural analysis.

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“…The yields refer to analytically pure compounds and were not optimized. The complexes 1 [9] and 2 [7], the aminoalcohols N,N-dimethyl alaninol (3), N,N-dimethyl leucinol (4), N,N-dimethyl valinol (5), N,N-dimethyl phenylalaninol ( 6), [10,11] and N-formylprolinol (7) [12] as well as PTol 3 [13] were prepared according to literature procedures. P(OMe) 3 and acetyl bromide were purchased from Fluka.…”

Section: Generalmentioning

confidence: 99%

Synthesis of chiral β-aminoalcohol-substituted carbene complexes of manganese and influence of the chiral carbene ligand on the diastereoselectivity of the CO/PR3 exchange

Weißenbach

Fischer

2001

Journal of Organometallic Chemistry

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The acetoxy(phenyl)carbene complex [Cp(CO) 2 Mn C(OAc)Ph] (2) reacts with chiral b-aminoalcohols HOR* [HOR* =N,Ndimethyl alaninol (3), N,N-dimethyl valinol (4), N,N-dimethyl leucinol (5), N,N-dimethylphenyl alaninol (6), and N-formylprolinol (7)] by displacement of the acetoxy substituent and formation of the b-aminoalkoxy(phenyl)carbene complexes [Cp(CO) 2 Mn C(OR*)Ph] (8-12). Irradiation of 9-12 in the presence of PR 3 (R =Ph, OMe) affords the carbene(carbonyl)cyclopentadienyl(PR 3 )manganese complexes [Cp(CO)(PR 3 )Mn C(OR*)Ph]. The substitution proceeds diastereoselectively, the diastereomeric excess ranging from 28% to \90%. The highest diastereoselectivity ( \ 90%) is observed in the reaction of 9 (R*= CH 2 C(NMe 2 )HCMe 2 H) with PR 3 . In solution, complex 9 is not stable configurationally and epimerizes within a few days. The reaction of 2 with HOC 2 H 4 SCH 2 Ph affords [Cp(CO) 2 Mn C(OC 2 H 4 SCH 2 Ph)Ph] (22) which, on photolysis, is transformed, by loss of a CO ligand, into a chelating carbene complex (24). In the presence of PR 3 compound 24 cannot be converted thermally into [Cp(CO)(PR 3 )Mn C(OC 2 H 4 SCH 2 Ph)Ph].

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EFFICIENT PREPARATION OF THE CHIRAL AUXILIARIESSAMPandRAMP.N-AMINATIONviaHOFMANN DEGRADATION

Cited by 40 publications

References 13 publications

A combined chemical-enzymic synthesis of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate

A combined chemical-enzymic synthesis of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate

Aminolysis of 3-alkoxysubstituted cyclobutenylidene complexes. A novel convenient route to chiral 3-aminosubstituted cyclobutenylidene complexes

Synthesis of chiral β-aminoalcohol-substituted carbene complexes of manganese and influence of the chiral carbene ligand on the diastereoselectivity of the CO/PR3 exchange

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