Rearrangements Connected with the Migration of Acyl and Certain Other Groups

Pavlova, L. V.; Rachinskii, F. Yu.

doi:10.1070/rc1968v037n08abeh001684

Cited by 38 publications

(27 citation statements)

References 183 publications

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“…28) Wodurch der Vorteil unserer Methode, wahlweise das Ioder das u-Isomere zu liefern, hinfallig ware! 29) S. auch die Anwendung in unserer Synthese des Lycorin-Gerustes [%I.…”

Section: )unclassified

“…: C 74,56, H 8.58, N 5,03. 2.5. u 45;137,OO;134,02;133,49;130,50;129,Ol;128,79;128,56;128,lO;127,48;127,07;78,46;59,06;42,27;39,10;29,14;28,36 9 arom. H); 5,98 (d, J = 3, CHN); 5,32 (d, J = 3, CHOH); 5,24 (s, OH); 3,96338 (1 H), 2,94-2,23 (3 H) (2m, CH2CH2); 1,25 (s, t-Bu).…”

Section: ( Tert-buiy~)-[i234-terrahydro-67-(dimethoxy) Isochinoliunclassified

“…s, CH-0); 4,14-3,88 (m, CH2N); 3,98 (s, CH30); 3,93 (s, CH30); 2,89-2,88 (m. ArCH,); 1,36 (s, t-Bu). ',C-NMR (20 MHz,CDC13): 177.57;152,87;147,Ol;145,44;140,71;129,14;122,39;119,57;118,50;117,28;108,49;106,76;100,82;83,74;62,29;58,05;56,88;42,43;39,15;29,13;28,18. MS: 454 ( < 1, MC' + I), 260 (90), 176 (39,1), 57 (100).…”

Section: U-[l-(2-brom-cc-hydrosy~-1234-tetrahydro-67-dimethoxyi~sunclassified

“…H); 5,92 (d,J = 7,05,4,32 (d,J = 7,05,CHN); 3,84 (s, CH,O); 3,14-2,59 (m, ArCHzCH2N); 1,18 (s,. ',C-NMR (20 MHz,CDCI,): 177,23;147,06;146,32;135,59;134,63;130,69;129,14;128,65;126,82;125,32;118,88;113,44;110.73;77,77;58,49;55,72;39,65;38,76;29,24;27,09. MS: 370 ( < 0.1, M" + l), 267 (2,3), 152 (2,1), 132 (IOO), …”

Section: 14 U-22-dimethylpropansaure-[a-(l234-tetrahydro-l-isounclassified

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Diasteroselektive Hydroxyalkylierungen in 1‐Stellung von Tetrahydroisochinolinen und Synthese von Aporphin‐, Protoberberin‐ und Phthalid‐Alkaloider

Seebàch¹,

Isabelle²,

Max³

1987

Helvetica Chimica Acta

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Unsubstituted and 6,7-dialkoxy-N-pivaloyl-tetrahydroisoqu~nolines 1-3 are converted to l-bromomagnesium derivatives by sequential treatment with 1-BuLi (-75"/THF) and MgBrz.0Et2. Addition of the metalated tetrahydroisoquinolines to aliphatic or aromatic aldehydes occurs with relative topicity ul (Scheme 2). The I-hydroxyalkylated 2-pivaloyl-tetrahydroisoquinolines a of u-configuration thus obtained (14 examples) can be converted to free aminoalcohols c of either Ior u-configuration (9 examples; Scheme 3). The depivdloylation with retention (+ u-c) is best achieved by heating in EtOH/KOH, the conversion to 1 -aminoalcohols I-c by treatment with CF,COOH/(CF,CO),O (+ I -pivalates I-b), followed by alkaline saponification or by LiAIH4 reduction of the esters. The configuration of the products is assigned by 'H-NMR spectroscopy, by X-ray crystal structure analysis, by chemical correlation, and by comparison of the chemical properties of the Iand the u-isomers. The diastereoselective hydroxybenzylation of the tetrahydroisoquinoline is used for short syntheses of ushinsunine/ oliveroline (Scheme 4 ) , p-hydrastine, and ophiocarpine/epiophiocarpine (Scheme 6: aporphine, phthalide, and protoberberine alkaloids, respectively).

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“…28) Wodurch der Vorteil unserer Methode, wahlweise das Ioder das u-Isomere zu liefern, hinfallig ware! 29) S. auch die Anwendung in unserer Synthese des Lycorin-Gerustes [%I.…”

Section: )unclassified

Section: ( Tert-buiy~)-[i234-terrahydro-67-(dimethoxy) Isochinoliunclassified

Section: U-[l-(2-brom-cc-hydrosy~-1234-tetrahydro-67-dimethoxyi~sunclassified

Section: 14 U-22-dimethylpropansaure-[a-(l234-tetrahydro-l-isounclassified

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Diasteroselektive Hydroxyalkylierungen in 1‐Stellung von Tetrahydroisochinolinen und Synthese von Aporphin‐, Protoberberin‐ und Phthalid‐Alkaloider

Seebàch¹,

Isabelle²,

Max³

1987

Helvetica Chimica Acta

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“…1 We tried to synthesize optically active compound 1 from nonracemic paracyclophane 2, which is accessible The evidence for this explanation is such processes as anionic O→C rearrangements in aryl carbamates 5,2 and O→O migrations of acyl groups in ali phatic and aromatic polyols. 6 Thus, we proposed the approach to the regioselective synthesis of racemic chiral monomethyl ether 1 in total 53% yield. The next task is to resolve it into enantiomers.…”

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Unexpected racemization in the series of 4,5-disubstituted [2.2]paracyclophanes

et al. 2005

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During the development of approaches to regio selective synthesis of novel types of planar chiral ligands from [2.2]paracyclophane, 1 we studied the possibility of obtaining 5 hydroxy 4 methoxy[2.2]paracyclophane (1), a chiral analog of guaiacol. For this purpose, we carried out ortho lithiation of racemic 4 carbamoyloxy[2.2]para cyclophane (2) (Bu s Li/THF, -78 °C) 2 followed by treatment of the reaction mixture with B(OMe) 3 and oxidation of the intermediate boronic derivative with a H 2 O 2 -NaOH system. 4 Carbamoyloxy 5 hydr oxy[2.2]paracyclophane (3) (70%) obtained for the first time was converted into the respective O methyl deriva tive 4 (NaH/DMF, then MeI). Selective elimination of the carbamoyl group from compound 4 (LiAlH 4 /ether) gave the target racemic ortho methoxyphenol 1 in 76% yield (Scheme 1).It is known 3 that the paracyclophane framework is very stable and racemization is possible only upon cleav age of the ethano bridges at T > 200 °C. Because of this, scalemic planar chiral compounds of this series can be obtained by transformations of the starting optically ac tive paracyclophane derivatives under typical conditions of fine organic synthesis. 1 We tried to synthesize optically active compound 1 from nonracemic paracyclophane 2, which is accessible from the enantiomers of 4 hydroxy[2.2]paracyclophane. 4 Unexpectedly, the aforementioned sequence of transfor mations of compound (S) 2 gave products 3, 4, and 1 with nearly zero optical rotation values and HPLC analy sis of compound 1 on a chiral phase revealed its racemic nature. Cleavage of the ethano bridges in paracyclophane is impossible under the reaction conditions used, which was experimentally confirmed by the retained optical ro tation value of partially recovered compound (S) 2. The observed racemization of o hydroxy derivative 3 (during its formation from (S) 2) can be explained by the O O migration of the carbamoyl group under basic conditions since intermediate paracyclophanes (R) B and (S) B formed in this case are enantiomers interconvertible through cyclic intermediate A (or, less probably, in an intermolecular way). The evidence for this explanation is such processes as anionic O→C rearrangements in aryl carbamates 5,2 and O→O migrations of acyl groups in ali phatic and aromatic polyols. 6 Thus, we proposed the approach to the regioselective synthesis of racemic chiral monomethyl ether 1 in total 53% yield. The next task is to resolve it into enantiomers. We discovered a novel type of racemization for paracyclo phane derivatives, which is associated with O O mi gration of the carbamoyl group in a basic medium.

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Acylgruppenwanderung, III. Enolester des 1‐Acyl‐2‐indanons

1975

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1-Acyl-2-indanone 2 reagieren mit Phosgen oder Chlorameisenstiure-phenylester zu den Dioxinonen 1 und mit Chlorthioameisensaure-0-phenylester zu den Dioxinthionen3. In siedenden Alkoholen werden l a und 3a in die Kohlensaure-enolestcr 9 und die ThiokohlensPure-Oenolester 13 ubergefuhrt. 1 -Acetyl-2-indanon (2a) kann auch rnit Chlorameisen~ureesternl Trilthylamin direkt zu 9 und mit Carbons&urechloriden entsprechend zu den Carbonsaureenolestern 11 umgesetzt werden. 1 a liefert rnit 1 mol Thiol/Trialkylamin die Thiokohlensiiure-S-enolester 10. Alle Enolester (4, 8, 9, 10, 11 und 13) liegen kristallin in der a-Form vor. Bei 9.10, 11 und 13 beobachtet man in Lasung ein Gleichgewicht mit dem p-homeren aufgrund einer schnellen intramolekularen 1,5-Acylgruppenwanderung. Durch Protonenkatalyse entsteht daneben noch das y-Isomere, das bei 9 b und 13b rein isoliert werden konnte. Der Ubergang $-Lsomeres Acyl Croup Migration, III1.2) Eaol Esters of l -A c y l -2 i n o n eCondensation of 1-acyl-2-indanones 2 with phosgene or phenyl chloroformate leads to the formation of dioxinones 1 and with 0-phenyl chlorothioformate to the formation of dioxinthiones 3. In boiling alcohols l a and 3a are transformed into the carbonic acid enol esters 9 and into the thiocarbonic acid 0-en01 esters 13. I-Acetyl-2-indanone (2a) can be condensed with chloroformic acid esters/triethylamine to form 9 directly, and with acyl chlorides to yield the carboxylic acid e n d esters 11. l a reacts with 1 mole of a thiol/trialkylamine to give the thiocarbonic acid S-enol esters 10. In the cristalline state all en01 esters (4, 8,9,10,11 and 13) exist in the a-form. In the case of 9,10,11 and 13 in solution a rapid equilibrium with the p-isomer is established by an intramolecular 1,S-acyl shift. By proton catalysis the y-isomer is formed in addition to the a-and p-isomer. 9 b y and 13by have been isolated in pure cristalh e torm. The configurational change p-isomer F?: y-isomer is also obtained photochemically. y-Isomeres wird auch photochemisch erreicht.Die intramolekulare Wanderung einer Acylgruppe unter Bildung des thermodynamisch stabileren Produktes ist bereits seit der Jahrhundertwende bekannt3). Diese Beobachtungen beziehen sich vornehmlich auf den Austausch der Acylgruppe zwi-1 ) 11.

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Rearrangements Connected with the Migration of Acyl and Certain Other Groups

Cited by 38 publications

References 183 publications

Diasteroselektive Hydroxyalkylierungen in 1‐Stellung von Tetrahydroisochinolinen und Synthese von Aporphin‐, Protoberberin‐ und Phthalid‐Alkaloider

Diasteroselektive Hydroxyalkylierungen in 1‐Stellung von Tetrahydroisochinolinen und Synthese von Aporphin‐, Protoberberin‐ und Phthalid‐Alkaloider

Unexpected racemization in the series of 4,5-disubstituted [2.2]paracyclophanes

Acylgruppenwanderung, III. Enolester des 1‐Acyl‐2‐indanons

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