Total synthesis of (±)-isoprosopinine B and (±)-desoxoprosopinine

Holmes, Andrew B.; Thompson, John L.P.; Baxter, Andrew; Dixon, John R.

doi:10.1039/c39850000037

Cited by 43 publications

(11 citation statements)

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“…10.5,8.8,H-C(5));3.50(t,J-9.2,H-C(4));3.49(ddd,J= 10.4,4.2,2.3,H-C(7));3.47 J = 9.1, H-C(3)); 3.89(ddd, J = 12. 2,6.3,2.5,H-C(8)); 3.82(dd,J = 11.2,2.0, H-C(10)); 3,78(dd,J = 11. 2,4.8, H'-C(IO)); 3.68 (dt, J = 12.0, 6.0, H-C(8)); 3.63 (dd, J = 10.…”

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confidence: 99%

“…IR (CHCI,): 3 5 9 7~ 3306s, 3007m, 2946s, 2894s, 2867s, 2260w, 2131~. 1464m, 1370m, 1327w, 1292m, 1260m, 1152s, 1098s, 1040s, 919s, 883s, 649s, 603w, 575w, 546w, 537w, 514w 79(ddd,J=11.5,6.0,2.1,H-C(8));3.68(dt,Js 11.6,5.3,H'-C(8));3.65(dd,J= 10.0,8.6,H-C(7')); 3,62(t, J = 9.1, H-C(4)); 3.54 (dd, J = 10. 3,9.7, H-C(5)); 3.50 (t, J = 9.4, H-C (6)); 3.49 (m, H-C(9')); 3.47 (s, 2 MeO); 3.45 (m, H-C (7)); 3.51 (s, MeO); 2.72 (Id, J = 10.5, 2.3, H-C(8')); 2.68 (br.…”

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confidence: 99%

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Oligosaccharide Analogues of Polysaccharides. Part 2. Regioselective deprotection of monosaccharide‐derived monomers and dimers

Alzeer

Vasella

1995

Helvetica Chimica Acta

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The Me$-C( 1) bond of the bis-(trimethylsily1)ethynylated anhydroalditol2 is selectively cleaved with BuLi to yield 3/4, while AgN02/KCN in MeOH cleaves the Me3Si-C(2') bond, leading to 5 (Scheme I ) . Both Me,Si groups are removed with NaOH in MeOH (+ 7), the (i-Pr)$i group is selectively cleaved with HC1 in aq. MeOH (+ 6 ) ; all silyl substituents are removed with Bu,NF (+ 8). Acetolysis transformed 9 into 13, which was desilylated to 14, while thiolysis of 9 led to a mixture 11/12. The tetraacetate 14 has also been obtained from 9 viu 10. Oxidative dimerisation of either 3 or 5, or of a mixture 3/57 yields only the homodimers 15 and 16 (Scheme 2); treatment of 16 with AgN02/KCN yielded 17, deprotection proceeding much more slowly than the cleavage of the Me,Si-C(Z') group of 2. The iodoalkyne 20, required for the cross-coupling with 5 according to Cadiof-Chodkiewicz, was prepared by deprotection of 3/4 to 18, methoxymethylation (+ 19), and iodination. Cross-coupling yielded mostly 21, besides the homodimer 22. Similarly, cross-coupling of 20 and 23 (obtained from 5) led to 24 and 22. The structure of 24 was established by X-ray analysis (Fig.), showing a C(6)-C(5') distance of 5.2 A. The conditions for deprotecting 2 were applied to 21, and led to 25 (AgN02/KCN), 26 (as. NdOH), 27 (Bu,NF), and 29 (HCI/MeOH; Scheme 3). Attempted deprotection of the propargylic-ether moiety with BuLi, however, failed. The dimer 27 was further deprotected to 28. Acetolytic (Ac,O/Me,SiOTf) debenzylation of the dimer 30, obtained from 10, gave 31 (83%) which was deacetylated to 32 (Scheme 4). Cross-coupling of 5 and the bromoalkyne 33, obtained from 10, yielded 34; again, acetolysis proceeded well, leading to 35. The cellobiose derivative 38 was prepared from the lactone 36 via 37. The glycosidic linkage of 38 proved resistant to the conditions of acetolysis, leading to 39. Acetolysis of the benzylated thiophene 40 (from 30 with Na,S) yielded the octaacetate 41, but proceeded in substantially lower yields (50%). J = 11.3, PhCH); 4.84 (d, J = 11.3, PhCH); 4.80 (d, J = 11.3, PhCH); 4.77 (d, J = 11.0, PhCH); 4.60 (d, J = 11.3, PhCH); 4.47 (d, J = 12.1, PhCH); 4.36 (d, J = 12.1, PhCH); 3.99 (dd, J = 9.6, 0.7, H-C(5')); 3.73 (d, J = 9.3, H-C(3)); 3.71 (t, J = 9.6, 9.2, H-C(8)); 3.66 ( t . J =9.3, H-C(4)); 3.65 (dd, J = 11.3, 3.9, H-C(10')); 3.64 (m, H-C(8)); 3.61 (dd, J = 11.1, 1.8, H'-C(lO')); 3.60 (t, J = 9.6, 9.2, H-C(6)); 3.48 (t, J = 9.0, H-C(7')); 3.45 (td, J = 12.4, 5.0, H'-C(8)); 3.22 (ddd, J = 10.4, 8.2, 3.9, H-C(5)); 3.17 (ddd, J = 9.8, 3.7, 1.9, H-C(9')); 2.96 (ddd, J = 10.2, 5.0, 2.3, H-C(7)); 2.53 (br. t, J = 10.3, H-C(6)); 1.88 (d, J =3.9, OH-C(5)); 1.37 (t. J = 6.3, OH-C(8)); 1.34-1.21 (m, (i-Pr),Si); 0.15 (s. Me,Si). 13C-NMR (50 MHz,

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confidence: 99%

mentioning

confidence: 99%

Oligosaccharide Analogues of Polysaccharides. Part 2. Regioselective deprotection of monosaccharide‐derived monomers and dimers

Alzeer

Vasella

1995

Helvetica Chimica Acta

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“…Furthermore, these products can be readily converted to the biologically active pipecolic acids (Krow et al 1982(Krow et al , 1999Holmes et al 1985). A retrosynthetic analysis shows that these isoquinuclidines 28 can be prepared from imines 29 and cyclohexenone 30 (Babu and Perumal 1998;Shi and Xu 2001;Sunden et al 2005).…”

Section: Synthesis Of Isoquinuclidinesmentioning

confidence: 99%

New Developments in Enantioselective Brønsted Acid Catalysis: Chiral Ion Pair Catalysis and Beyond

Rueping¹,

Sugiono²

2008

Ernst Schering Foundation Symposium Proceedings

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“…The solution was stirred for 1.5 h and quenched with water (5 mL). After separation, the organic layer was washed with a saturated NaHCO 3 solution (2 ϫ 5 mL) and brine (5 mL), and then dried with anhydrous MgSO 4 . The solvent was distilled and the residue purified by chromatography (silica gel, hexane/EtOAc: 10:1) to afford 10 (99 mg, 78 %) as a colorless oil.…”

Section: Synthesis Of 26-substituted 3-piperidinol Derivative 7 (1rmentioning

confidence: 99%

“…[2] Different methods that allow the formation of a piperidine ring [3] in racemic [4] or in enantioenriched forms have been described. Some of these strategies employed an asymmetric synthesis methodology, [5] but in most approaches an enantiopure substance was used as the starting material: amines, [6] amino acids, [7] and sugar derivatives [8] have been the most commonly used starting materials.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Enantioenriched 2‐ and 2,6‐Substituted Piperidin‐3‐ols from α‐Dibenzylamino Aldehydes

2007

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Total synthesis of (±)-isoprosopinine B and (±)-desoxoprosopinine

Cited by 43 publications

References 1 publication

Oligosaccharide Analogues of Polysaccharides. Part 2. Regioselective deprotection of monosaccharide‐derived monomers and dimers

Oligosaccharide Analogues of Polysaccharides. Part 2. Regioselective deprotection of monosaccharide‐derived monomers and dimers

New Developments in Enantioselective Brønsted Acid Catalysis: Chiral Ion Pair Catalysis and Beyond

Synthesis of Enantioenriched 2‐ and 2,6‐Substituted Piperidin‐3‐ols from α‐Dibenzylamino Aldehydes

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