Synthesis of <scp>D</scp>‐ and <scp>L</scp>‐5‐Oxaproline and of a New Captopril Analogue

Vasella, Andrea; Voeffray, Robert; Pless, J.; Huguenin, R

doi:10.1002/hlca.19830660424

Cited by 51 publications

(21 citation statements)

References 17 publications

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“…Duten uon (1)); 4,84 (dd, J = 3,7, 5,6, H-C(2)); 4,77 (dd, J = 3,4, 5,7, H-C(3)); 4,46 (td, J = 5,2, 7,7, H-C(5)); 4,12 (d, J = 5,2, 2 H-C(6)) ; 3,57 (dd, J = 3.4, 7,7 H-C(4)); 2,50 (s, MeS); I J I ,1,45,1,38,1,34,(4.7,4 Me H-C(1)); 4,80 (dd, J = 3,4, 6,0, H-C(3)); 4,71 (d, J = 6,0, H-C(2)); 4,46 (ddd, J = 4,6, 6,0, 7,0, H-C(5)); 4,12 (dd, J = 6,0, 9,0, H-C(6)); 4,064,11 (m, H-C(4)); 4,04 (dd, J = 4,6, 9,0, H'-C(6)); 2,48 (s, MeS); 1,49,1,46,1,38,1,34 (4s,4 Me Bis (2,3:5,6-di-O-isopropy/iden-B-o-munnofuruno.~).l) -di.sulfid (1 3) und (2,3:5, (27), 85 (17), 59 (15), 43 (40). Anal.…”

Section: Experimenteller Teilmentioning

confidence: 98%

“…: C 56,79,H 7,38,S 14,19. (2,3:5, (2,3:5,. Eine Suspension von NaOEt (12 mmol) in THF') wurde mil 3,65 g (10 mmol) 8 versetzt und bei 50" bis zum volligen Umsatz geruhrt.…”

Section: Experimenteller Teilunclassified

“…Bi.~ (2,3:5,3:5, - (2,3:5,6- 2 3 0~, 11643, 1 101s, 1043s, 947.7, 910nv, 84711). (6)); 4,07 (dd, J = 6,0, 9,0, H'-C(6)); 3,51 (dd, J = 3,3, 7,4, H-C(4)); 1,26-1,78 (m. 20 H 4,36-4,50 (m, H-C(5), H-C(5')); 4,16 (ddd, J = 0,5, 3,5, 6,0, H-C(4)); 3,994,lO (m, 4 H); 3,54 (dd, J = 3,5, 7,5, H-C(4)); 1,50-1,70 (m. 40 H).…”

mentioning

confidence: 97%

“…Die Konformation des Glycosyl-Teils mit einer tg-Anordung von O(2)') gleicht stark dem entsprechenden Glycosyl-Rest von 13. Dagegen weist die Disulfid-Gruppe wie bei 11 (P)-Chiralitlt auf, wobei auch der Torsionswinkel H-C(l)-S(l)-S (2) (35") gleich gross wie derjenige von 11 ist.…”

unclassified

“…Unter H,O-freien Bedingungen wurde eine auf -40" gekuhlte Lsg. von 1,08 g (2 mmol) 18 und 0,386 ml (4 mmol) CC1, in 10 ml CH,Cl, tropfenweise rnit 0,545 ml (3 mmol = 8,0,2,25 H,Me).…”

unclassified

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Glycosylsulfenyl‐ und (Glycosylthio)sulfenyl‐halogenide (Halogeno‐ bzw. Halogenothio‐(1‐thioglycoside)): Herstellung und Umsetzung mit Alkenen

Hürzeler

Bernet

Vasella

1992

Helvetica Chimica Acta

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Glycosylsulfenyl and (Glycosylthio)sulfenyl Halides (Halogeno and Halogenothio 1-Thioglycosides, Resp.): Preparation and Reaction with AlkenesThe disulfides 11-17 and 20 were prepared from 7, 9, and 18 via the dithiocarbonates 8, 10, and 19, respectively (Scheme 2 ) . The structure of 11 and of 13 was established by X-ray analysis. Chlorolysis (SO,Cl,) of 1 1 gave mostly the sulfenyl chloride 24, characterized as the sulfenamide 26, a small amount of 21, characterized as the (g1ycosylthio)sulfenamide 23, and the glycosyl chloride 27 (Scheme 3). Bromolysis of 11 followed by treatment of the crude with PhNH, yielded only 28. Chlorolysis of the diglycosyl disulfide 13, however, gave mostly the (g1ycosylthio)sulfenyl chloride 21 and 27, besides 24. Bromolysis of 13 (-22 and traces of 25) followed by treatment with PhNH, gave an even higher proportion of 23. Similarly, 20 led to 29 and hence to 30. In solution (CHfJ,), the sulfenyl chloride 24 decomposes faster than the (thio)sulfenyl chloride 21, and both interconvert. Addition of crude 24 to styrene (-78O) yielded the chloro-sulfide 31 and some 37, both in low yields. The product of the addition of 24 to 1-methylcyclohexene was transformed into the trio1 32. Silyl ethers of allylic alcohols reacted with 24 only at room temperature, yielding, after desilylation, isomer mixtures 33 and 34, and pure 35. Much higher yields were achieved for the addition of (thio)sulfenyl halides yielding halogeno-disulfides. Good diastereoselectivities were only obtained with 21, its cyclohexylidene-protected analogue, and 22, and this only in the addition to styrene (+ 36, 37, 38), to (E)-disubstituted alkenes (+ 46, 48, 49a/b, 50a/b, 53), and to trisubstituted alkenes (+ 47,51,52,54,55). Other monosuhstituted alkenes (+ 4145) and (Z)-hex-2-ene (+ 49c/d, 50c/d) reacted with low diastereoselectivities. Where structurally possible, a stereospecific trans-addition was observed; regioselectivity was observed in the addition to mono-and trisubstituted alkenes and to derivatives of ally1 alcohols. The absolute configuration of the 2-chloro-disulfides was either established by X-ray analysis (47a) or detcrmined by transforming (LiAlH,) the chloro-disulfides into known thiiranes (Scheme 5 ) . Thus, 37,48, and the mixture of 49a/b and 50a/b gave the thiiranes 56,61, and 64, respectively, in good-to-acceptable yields (Scheme 5 ) . Harsher conditions transformed 56 into the thiols 57 and 58. Similarly, 61 gave 62. The enantiomeric excesses of these thiols were determined by GC analysis of their esters obtained with (-)-camphanoyl chloride. Addition of 21 to ([(E)-hex-2-enyl]oxy}trimethylsilane, followed by LiAIH, reduction and desilylation, gave the known 66 (63 %, e.e. 74%). The diaslereoselectivity of the addition of 21 to trans-disubstituted and trisubstituted alkenes is rationalized by assuming a preferred conformation of the (thio)sulfenyl chloride and destabilizing steric interactions with one of the alkene substituents, while the diastereoselectivity of the addition to styrene is explained...

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Section: Experimenteller Teilmentioning

confidence: 98%

“…: C 56,79,H 7,38,S 14,19. (2,3:5, (2,3:5,. Eine Suspension von NaOEt (12 mmol) in THF') wurde mil 3,65 g (10 mmol) 8 versetzt und bei 50" bis zum volligen Umsatz geruhrt.…”

Section: Experimenteller Teilunclassified

mentioning

confidence: 97%

unclassified

“…Unter H,O-freien Bedingungen wurde eine auf -40" gekuhlte Lsg. von 1,08 g (2 mmol) 18 und 0,386 ml (4 mmol) CC1, in 10 ml CH,Cl, tropfenweise rnit 0,545 ml (3 mmol = 8,0,2,25 H,Me).…”

unclassified

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Glycosylsulfenyl‐ und (Glycosylthio)sulfenyl‐halogenide (Halogeno‐ bzw. Halogenothio‐(1‐thioglycoside)): Herstellung und Umsetzung mit Alkenen

Hürzeler

Bernet

Vasella

1992

Helvetica Chimica Acta

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Convenient Preparation of α-Amino Acids with Bicyclopropylidene and Other Methylenecyclopropane Moieties

et al. 1998

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Racemic bicyclopropylidenyl‐ (rac‐11) and methylenespiropentyl‐ (rac‐17) substituted alanines have been synthesized by iodination of bicyclopropylidenyl‐ and methylenespiropentylmethanols 7, 13, nucleophilic substitution of the iodine in 8, 14 with the enolate of ethyl α‐(diphenylmethyleneamino)acetate (O'Donnell's glycine equivalent) and deprotection of 9, 15 in 24 and 18% overall yield, respectively. N‐Methylbicyclopropylidenylalanine rac‐22, was obtained from the Michael adduct of (bicyclopropylidenyl)magnesium bromide 18 to enamine 19 and deprotection of the carbamate 20 (23% overall yield). Racemic (1‐amino‐2‐methylenespiropentane)‐ (37), (1‐amino‐2‐methylenecyclopropane)‐ (3), and (1‐aminobicyclopropylidene)carboxylic acid (39) were prepared as hydrochlorides by tert‐butoxycarbonylation of the lithiated methylenespiropentane (6), methylenecyclopropane (4), or bicyclopropylidene (5) intermediates with di‐tert‐butyl pyrocarbonate (Boc2O), repeated lithiation of the tert‐butyl esters 29, 30, and 33 with LDA and subsequent carboxylation, Curtius degradation of the half esters 31, 32, and 34 followed by deprotection in 11, 45, and 4% overall yields, respectively. Compound 37 was also prepared from bicyclopropylidene (5) following the same procedure, but with rearrangement in the last but one step, in 19% overall yield. An attempted Hofmann degradation of the bicyclopropylidenecarboxamido ester 40 with NBS failed and gave only bromohydrin 44 (27%), but with bis(acetoxy)iodobenzene provided carbamate 46a, b in 76 amd 79% yield, respectively. Along this route with subsequent deprotection of 46b, the amino acid 39 could be prepared in up to 10% overall yield from bicyclopropylidene.

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Ethylene

Crimmins

Kim‐Meade

2001

Encyclopedia of Reagents for Organic Synthesis

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Synthesis of D‐ and L‐5‐Oxaproline and of a New Captopril Analogue

Cited by 51 publications

References 17 publications

Glycosylsulfenyl‐ und (Glycosylthio)sulfenyl‐halogenide (Halogeno‐ bzw. Halogenothio‐(1‐thioglycoside)): Herstellung und Umsetzung mit Alkenen

Glycosylsulfenyl‐ und (Glycosylthio)sulfenyl‐halogenide (Halogeno‐ bzw. Halogenothio‐(1‐thioglycoside)): Herstellung und Umsetzung mit Alkenen

Convenient Preparation of α-Amino Acids with Bicyclopropylidene and Other Methylenecyclopropane Moieties

Ethylene

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