Reaktionen mit phosphororganischen Verbindungen. XLII. Nucleophile Substitutionen an Hydroxysteroiden mit Hilfe von Triphenylphosphan/Azodicarbonsäureester

Nucleophilic Substitution Reactions of Hydroxysteroids using Triphenylphosphane/diethylazodicarboxylate Nucleophilic substitution reactions by means of the title reagent on various more or less hindered steroid alcohols with suitable nucleophils in benzene is described. It was not possible to run this substitution process in the hitherto used solvent THF. Cholestan-3α-ol ( 1 ) was transformed to the 3β-substituted products 3β-benzoyloxy-cholestane ( 1a ) and 3β-azido-cholestane ( 1b ). Testosterone ( 2 ) affords with the corresponding nucleophils after short heating in benzene the inverted 17α-substituted products 3a, 3b and 3c . Analogously the 17α-azido-derivative 5a arises from 17β-hydroxy-androst-3-on ( 4 ). In the presence of a ketogroup in the substrate a competitive reaction can occur as it is shown in the case of cholestan-3-on ( 6 ): the products are the en-hydrazo-dicarboxylate-steroids 7a and 7b . The sterically very hindered 11α-position in 11α-hydroxy-4-pregnen-3,20-dion ( 8 ) can be transformed also to the 11β-azide 9a . The substitution of a 6 β-hydroxy group in androstane-3β, 6β, 17β-triol-3,17-diacetate ( 10 ) to the 6α-azide 11a affords the elimination product 12 as main component. Trans-diaxial vicinal diols such as cholestane-2β,3α-diol ( 13 ) give a mixture of the α- and β-oxiranes 14a and 14b .     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphin/Azodicarbonsäure-diäthylester. 3. Mitteilung [1]

Structural Modification on Partially Silylated Carbohydrates by Means of Triphenylphosphine/Diethyl Azodicarboxylate Reaction of methyl 2, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1a ) with triphenylphosphine (TPP)/diethyl azodicarboxylate (DEAD) and Ph₃P · HBr or methyl iodide yields methyl 3-bromo-2, 6-bis-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 3a ) and the corresponding 3-deoxy-3-iodo-alloside 3c (Scheme 1). By a similar way methyl 2, 6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2a ) can be converted to the 4-bromo-4-deoxy-galactoside 4a and the 4-deoxy-4-iodo-galactoside 4b . In the absence of an external nucleophile the sugar derivatives 1a and 2a react with TPP/DEAD to form the 3,4-anhydro-α- or -β-D -galactosides 5 and 6a , respectively, while methyl 4, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1b ) yields methyl 2,3-anhydro-4, 6-bis-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 7a , s. Scheme 2). Even the monosilylated sugar methyl 6-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2b ) can be transformed to methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 8 ; 56%) and 3,4-anhydro-α-D -alloside 9 (23%, s. Scheme 3). Reaction of 1c with TPP/DEAD/HN₃ leads to methyl 3-azido-6-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 10 ). The epoxides 7 and 8 were converted with NaN₃/NH₄Cl to the 2-azido-2-deoxy-altrosides 11 and 13 , respectively, and the 3-azido-3-deoxy-glucosides 12 and 14 , respectively (Scheme 4 and 5). Reaction of 7 and 8 with TPP/DEAD/HN₃ or p-nitrobenzoic acid afforded methyl 2,3-anhydro-4-azido-6-O-(t-butyldimethylsilyl)-4-deoxy-α- and -β-D -gulopyranoside ( 15 and 17 ), respectively, or methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-4-O-(p-nitrobenzoyl)-α- and -β-D -gulopyranoside ( 16 and 18 ), respectively, without any opening of the oxirane ring (s. Scheme 6). - The 2-acetamido-2-deoxy-glucosides 19a and 20a react with TPP/DEAD alone to form the corresponding methyl 2-acetamido-3,4-anhydro-6-O-(t-butyldimethylsilyl)-2-deoxy-galactopyranosides ( 21 and 22 ) in a yield of 80 and 85%, respectively (Scheme 7). With TPP/DEAD/HN₃ 20a is transformed to methyl 2-acetamido-3-azido-6-O-(t-butyldimethylsilyl)-2,3-didesoxy-β-D -allopyranoside ( 25 , Scheme 8). By this way methyl 2-acetamido-3,6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 19b ) yields methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-α-D -galactopyranoside ( 23 ; 16%) and the isomerized product methyl 2-acetamido-4,6-bis-O-(t-butyldimethylsilyl)-2-deoxy-α-D -glucopyranoside ( 19d ; 45%). Under the same conditions the disilylated methyl 2-acetamido-2-deoxy-glucoside 20b leads to methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-β-D -galactopyranoside ( 24 ). - All Structures were assigned by ¹H-NMR. analysis of the corresponding acetates.     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphan/Azodicarbonsäurediethylester, 4. Mitt.: Transformationen an Mannose und Galaktose

Reaction of methyl -D-galactopyranoside (1) with two equivalents oft-butyldimethylchlorosilane yields methyl 2,6-bis-O-(tBDMSi)--D-galactopyranoside (1 b), methyl 3,6-bis-O-(tBDMSi)--D-galactopyranoside (1 c) and methyl 4,6-bis-O-(tBDMSi)--D-galactopyranoside (1 d). Likewise methyl -D-mannopyranoside (6) affords methyl 2,6-bis-O-(tBDMSi)--D-mannopyranoside (6 d) and methyl 3,6-bis-O-(tBDMSi)--D-mannopyranoside (6 b), which can be isomerised withTPP/DEAD to methyl 4,6-bis-O-(tBDMSi)--D-mannopyranoside (6 f). Methyl 6-O-(tBDMSi)--D-galactopyranoside (1 a) and methyl 6-O-(tBDMSi)--D-mannopyranoside (6 a) can be prepared from1 or6 with one equivalent oft-butyldimethylchlorosilane.Without an external nucleophile the sugar derivatives1 a and1 b react withTPP/DEAD to form the 3,4-carbonato--D-galactopyranosides1 h and1 i and the 3,4-carbonato-2-O-ethoxycarbonyl--D-galactoside (1 j). In contrast to the formation of the compound1 i by means ofTPP/DEAD the reaction of1 a withTPP and Di-t-butyl-azodicarboxylate (DTBAD) yields the 2,3-anhydro--D-taloside (4 b) and only a small amount of1 i. The epoxide4 b can be cleaved withp-nitrobenzoylchloride/pyridine to the 3-chloro-3-deoxy-2,6-di-O-p-nitrobenzoyl--D-idoside (5). Reaction of1 c and1 d withTPP/DEAD yields the 2,3-anhydro--D-gulopyranoside (2), which can be transformed with NaN₃/NH₄Cl to the 2-azido-2-deoxy--D-idopyranoside (3).Likewise6 a and6 d can be converted to the 3,4-anhydro--D-talosides (7 a and7 b). Reaction of7 b or6 d withTPP/DEAD/NH₃ leads to 3,4-anhydro-2-azido-2-deoxy--D-galactopyranoside (8) and 3-azido-3-deoxy--D-altropyranoside (10), resp.The epoxide7 b is opened with NaN₃/NH₄Cl to the 4-azido-4-deoxymannosides (11 a and11 c) and the 3-azido-3-deoxy--D-idopyranoside (12), while the epoxide8 affords the 2,4-di-azido-2,4-dideoxy--D-glucopyranoside (9).Structures were elucidated by¹H-NMR-analysis of the corresponding acetates.

H. H. Brandstetter undE. Zbiral, Helv., im Druck.     

Zur herstellung aromatischer phosponsäureester aus arylhalogeniden und trialkylphosphiten

Aromatic iodo- or bromo-compounds react with with an excess of trialkylphosphite and copper to give the dialkylarylphosphonates 1a–1h. A radical mechanism is proposed for this reaction.     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphan-Azodicarbonsäureester, 5. Mitt.: Transformationen an Glykonolactonen

Reaction ofD-glucono-1,5-lactone1 with two equivalents oft-butyldimethylchlorosilane yields via a ringcontraction 2,6-bis-O-(t-BDMSi)-D-glucono-1,4-lactone2a as main product and a small amount of 5,6-bis-O-(t-BDMSi)-D-glucono-1,4-lactone2c. Under the same conditionsL-mannono-1,4-lactone3 is transformed to the derivatives 2,6-bis-O-(t-BDMSi)-L-mannono-1,4-lactone3a and 3,6-bis-O-(t-BDMSi)-L-mannono-1,4-lactone3c as the minor product. 2,6-bis-O-(t-BDMSi)-D-galactono-1,4-lactone4a and 2,6-bis-O-(t-BDMSi)-D-gulono-1,4-lactone5a are also prepared from the corresponding glyconolactones4 and5. Whereas the compounds2a, 2c, 4a and5a withAc ₂O-pyridine give the bisacetylderivatives2b, 2d, 4b and5b, 3c is converted by an accompanying migration of one silylgroup to the 5,6-bis-O-(t-BDMSi)-2,3-bis-O-acetyl-L-mannono-1,4-lactone3d. The gluconolactone derivative2a reacts easily withTPP/DEAD/HX to the 5-X-L-idono-1,4-lactone derivatives6a (X=N₃),6b (X=p-NO₂-C₆H₄COO) and6c (3-O-acetylderivative of6a). Treating6b with a second equivalentTPP/DEAD/HX leads to the unsaturated sugarlacton7b. Without an external nucleophile2a affords withTPP the mixture of 2,6-bis-O-(t-BDMSi)-3,5-carbonato-D-glucono-1,4-lactone2c, 3,5-anhydro-L-idono-1,4-lactone8 and 3,6-anhydro-D-glucono-1,4-lactone9. Analogous procedures applied to4a yield theL-altronolactonoderivatives10a, 10b and10c, the unsaturated sugarlactone11b on the one and the 3,5-carbonatogalactonolactone4c and the 2,6-bis-O-(t-BDMSi)-3-desoxy-5-ethoxycarbonyl-D-threo-hex-2-en-1,4-lactone12 on the other hand.Whereas the bis-silyletherderivative3a is transformed by the title system exclusively by an elimination process to13, the derivative5a affords withTPP/DEAD without any elimination the 3,6-anhydrosugar14. Partial desilylation of14 followed by acetylation gives the derivatives14a and14b.Structural elucidations were achieved by¹H-NMR-analysis. In some cases also CD-measurements allowed suitable correlations.

Mark, E., Zbiral, E., Brandstetter, H. H., 4. Mitt., Mh. Chem.111, 289 (1980).     

Zur Erhöhung der Reaktivität von apatitischen Rohphosphaten durch mechanische Aktivierung

Increase in the Reactivity of Apatitic Phosphates due to Mechanical Activation The lattice of natural apatitic phosphates was severely distorted by mechanical activation. At a high energy concentration in a centrifugal mill the crystals reach the X-ray amorphous state. The structural changes are investigated by infrared and X-ray methods. At increased degrees of activation the mechanically activated apatitic phosphates show enhanced solubility as a result of structural changes.     

Synthese makrocyclischer Arsenigsäureester

Synthesis of Macrocyclic Arsinous Acid Esters The reactions of alcoholamines and thioglykol, respectively, with aminoarsines lead to the formation of 8- and 10-membered, cyclic arsinous acid esters. The reaction of different acid NH, OH and SH groups with aminoarsines are examined. I.r. and ¹H n.m.r. data are presented and discussed.     

Azodicarbonsäureester und Diazoessigester als Reaktionspartner des Ferriophosphaalkens [Cp*(CO)2FeP=C(Ph)NMe2]

Azodicarboxylates and Diazoacetates as Reactants of the Ferriophosphaalkene [Cp*(CO)₂FeP=C(Ph)NMe₂] Reaction of equimolar amounts of the ferriophosphaalkene [Cp*(CO)₂FeP=C(Ph)NMe₂] ( 1 ) and diethyl azodicarboxylate afforded the complex (C₅Me₄CH₂)(CO)₂Fe ( 3 ) as the result of a cheletropic [1+4] cycloaddition with subsequent transprotonation. The diazoacetates N₂=CHCO₂R ( 8a :=tBu; 8b :Et) and 1 gave rise to the formation of the N‐metallated 1, 2, 3‐diazaphospholes [Cp*(CO)₂Fe‐ ] ( 11a, b ). Compounds 3, 11a and 11b were characterized by means of elemental analyses and spectroscopy (IR, ¹H, ¹³C{¹H}, ³¹P{¹H}‐NMR). The molecular structure of 11a was determined by X‐ray diffraction analysis.     

Offene und cyclische Methylstibonigsäureester. II

Esters of Methylstibonous Acid. II. The reaction of methyldibromstibine with sodium alcoholates and phenolates yield methyldialkoxi and methyldiphenoxistibines. Interchange reactions of the methyldiethoxistibine with thiols, 1,2-diols, 1,2-dithiols, and 2-mercapto-1-oles form dithioesters and cyclic esters of the methylstibonous acid in nearly quantitativ amount and high purity.