Beiträge zur Chemie des Phosphors. 134. Über die Triphosphane H(t-BuP)3H,Li(t-BuP)3Li und Me3Si(t-BuP)3SiMe3

Contributions to the Chemistry of Phosphorus. 134. On the Triphosphanes H(t-BuP)₃H' Li(t-BuP)₃Li, and Me₃Si(t-BuP)₃SiMe₃ The reaction of 1,3-diiodo-1,2,3-tri-tert-butyltriphosphane, I(t-BuP)₃I, with lithium aluminium hydride leads to 1,2,3-tri-tert-butyltriphosphane, H(t-BuP)₃H ( 1 ). 1 reacts with n-butyllithium to 1,3-dilithium-1,2,3-tri-tert-butyltriphosphide, Li(t-BuP)₃Li ( 2 ), which reacts further with trimethylchlorosilane yielding 1,3-bis(trimethylsilyl)-1,2,3-tri-tert-butyltriphosphane, Me₃Si(t-BuP)₃SiMe₃ ( 3 ). The triphosphanes 1, 2 and 3 could be isolated in a pure state. In solution 1 forms the threo, threo and the threo,erythro configurated diastereomers 1a and 1b in a ratio of about 2:1. 3 predominantly exists in form of the threo,erythro configurated diastereomer 3b by steric reasons.     

Zur Synthese sulfonierter Derivate von 2-Amino-p-xylol

Synthese of sulfonated derivatives of 2-amino-p-xylene Sulfonation of 2-amino-p-xylene (2) gave 2-amino-p-xylene-5-sulfonic acid (1) . The 2-amino-p-xylene-6-sulfonic acid (3) was prepared via three routes: (1) sulfonation of 2-amino-5-chloro-p-xylene (19) to 5-amino-2-chloro-p-xylene-3-sulfonic acid (20) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2-amino-6-nitro-p-xylene (21) to 2-nitro-p-xylene-6-sulfonyl chloride (11) followed by hydrolysis to 2-nitro-p-xylene-6-sulfonic acid (4) and Béchamp reduction; (3) Béchamp reduction of 2-chloro-3-nitro-p-xylene-5-sulfonic acid (13) to 3-amino-2-chloro-p-xylene-5-sulfonic acid (16) and subsequent hydrogenolysis. Catalytic reduction of 13 in aqueous sodium carbonate solution gave mixtures of 3 and 16 . 2-Amino-p-xylene-3-sulfonic acid (27) was synthesized via two routes: (1) reaction of 19 with sulfamic acid to 2-amino-5-chloro-p-xylene-3-sulfonic acid (26) followed by hydrogenolysis; (2) sulfur dioxide treatment of the diazonium salt derived from 2-amino-3-nitro-p-xylene (28) to 2-nitro-p-xylene-3-sulfonyl chloride (12) , hydrolysis to 2-nitro-p-xylene-3-sulfonic acid (7) and Béchamp reduction.     

Isolation and Structural Study on Carbohydrates from Cynanchum otophyllum and Cynanchum paniculatum

Three new carbohydrates were isolated from the acidic hydrolysis part of the ethyl acetate extract of Cynanchum otophyllum Schneid (Asclepiadaceae) and one new carbohydrate from the ethyl acetate extract of Cynanchum paniculatum Kitagawa. Their structures were determined as methyl 2,6-dideoxy-3-O-methyl-α-D-arabino-hexopyranosyl-(1 → 4)-2,6-deoxy-3-O-methyl-β-D-arabino-hexopyranosyl-(1 → 4)-2,6-dideoxy-3-O-methyl-α-D-arabino-hexopyranoside (1), ethyl 2,6-dideoxy-3-O-methyl-β-D-ribo-hexopyranosyl-(1 → 4)-2,6-dideoxy-3-O-methyl-α-l-lyxo-hexopyranoside (2), met hyl 2,6-dideoxy-3-O-methyl-α-l-ribo-hexopyranosyl-(1 → 4)-2,6-dideoxy-3-O-methyl-β-D-lyxo-hexopyranosyl-(1 → 4)-2,6-dideoxy-3-O-methyl-α-D-arabino-hexopyranoside (3), and 2,6-dideoxy-3-O-methyl-β-D-ribo-hexopyranosyl-(1 → 4)-2,6-dideoxy-3-O-methyl-α-d-arabino-hexopyranosyl-(1 → 4)-2,6-dideoxy-3-O-methyl-α -d-arabino-hexopyranose (4), respectively, by spectral methods.     

Raspailynes,Novel Long-Chain Acetylenic Enol Ethers of Glycerol from the Marine Sponges Raspailia pumila and Raspailia ramosa

The sponges Raspailia pumila and ramosa (Demospongiae, Tetractinomorpha, Axinellida) from the North-East Atlantic are shown to contain a series of novel long-chain enol ethers of glycerol where the enol ether C?C bond is conjugated, in sequence, to both an acetylenic and an olefinic bond. Polar extracts give raspailynes hydroxylated at their (1Z5Z)-1,5-alkadien-3-ynyl chain, like raspailyne Al ( = (+)-(S)-3-[((1Z,5Z)-16-hydroxy-hexadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; (+ 2 ) and isoraspailyne A ( = (+)-3-[((1Z,5Z)-17-hydroxyocta-deca-1,5-dien-3-ynyl)oxy]-1,2-[propanediol; (+)- 3 ). Less polar extracts give 3 different types of raspailynes not hydroxylated at the chain. Raspailynes of the first type have either the (1Z,5Z)-configuration in a linear chain such as raspailyne B2 (( = (?)-(s)-3-[((1Z,5Z)-trideca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; (?)-4), raspailyne Bl ( = (?)-3-[((1Z,5Z)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol;(?)- 5 ), and raspailyne B ( = 3-[((1Z,5Z)-pentadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 6 ) or the (1Z,5Z)-pentadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 6 )or the (1Z,5Z)-configuration in a chain ending with an isopropyl group, like isoraspailyne Bl ( = 3-[((1Z,5Z)-12-methyltrideca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 7 ) and isoraspailyne B ( = 3-[((1Z,5Z)-13-methyltetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 8 ). Raspailynes of the second type have the (1Z,5E)-configuration, like isoraspailyne Bla ( =3-[((1Z,5E)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 9 ) and isoraspailyne Ba ( = 3-[((1Z,5E)-13-methyltetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 10 ). Raspailynes of the third type have the (1E,5Z)-configuration, like isoraspailyne Blb ( = 3-[((1E,5Z)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2,-propanediol; 11 ). The (S)-configuration for (+)- 1 ,((+)- 2 , and (?)- 4 is derived from chemical correlations.     

Synthese von optisch aktiven,natürlichen Carotinoiden und strukturell verwandten Naturprodukten. V. Synthese von (3R, 3′R)-, (3S, 3′S)- und (3R,3′S; meso)-Zeaxanthin durch asymmetrische Hydroborierung. Ein neuer Zugang zu Optisch aktiven Carotinoidbausteinen. Vorläufige Mitteilung

Synthesis of Optically Active Natural Carotenoids and Structurally Related Compounds. V. Synthesis of (3R, 3′R)-, (3S, 3′S)- and (3R,3′S; meso)-zeaxanthin by Asymmetric Hydroboration. A New Approach to Optically Active Carotenoid Building Units The synthesis of (3R, 3′R)-, (3S, 3′S)- and (3R,3′S; meso)-zeaxanthin ( 1 ), ( 19 ) and ( 21 ) is reported utilizing asymmetric hydroboration as the key reaction. Thus, safranol isopropenylmethylether ( 4 ) is hydroborated with (+)- and (?)-(IPC)₂BH to give the optically pure key intermediates 5 and 7 resp., which are transformed into the above-mentioned C₄₀-compounds.     

Stereoselective and Enantioselective Syntheses of the Four Stereoisomers of Muscol from (3RS)‐Muscone

Two trans stereoisomers of 3‐methylcyclopentadecanol (=muscol), (1R,3R)‐ 2 and (1S,3S)‐ 2 , were efficiently synthesized from (3RS)‐3‐methylcyclopentadecanone (=muscone; (3RS)‐ 1 ) by a highly stereoselective reduction (Scheme). L‐Selectride^® (=lithium tri(sec‐butyl)borohydride) was used, followed by the enantiomer resolution by lipase QLG (Alcaligenes sp.). The cis stereoisomers of muscol, (1S,3R)‐ 2 and (1R,3S)‐ 2 , were obtained by the Mitsunobu inversion of (1R,3R)‐ 2 and (1S,3S)‐ 2 , respectively (Scheme). The absolute configuration of (1R,3R)‐ 2 was determined by X‐ray crystal‐structure analysis of its 3‐nitrophthalic acid monoester, 2‐[(1R,3R)‐3‐methylcyclopentadecyl hydrogen benzene‐1,2‐dicarboxylate ((1R,3R)‐ 3b ), and by oxidation of (1R,3R)‐ 2 to (3R)‐muscone.     

Preparation of 5-substituted- and 3,5-disubstituted-s-triazolo[4,3-a]pyridines

Cyclization of N-acyl-N′-(6-chloropyrid-2-yl)hydrazines ( 2a-2e ) with phosphorus oxychloride has produced several 5-chloro-s-triazolo[4,3-a]pyridines ( 3a-3e ). Nucleophilic displacement of the chlorosubstituent of 5-chloro-s-triazolo[4,3-a]pyridine ( 3a ) availed the 5-ethoxy ( 4a ) and 5-thioethoxy ( 4b ) derivatives and di(s-triazolo[4,3-a]pyrid-5-yl)sulfide ( 8 ) while reaction of 5-ethylsulfonyl-s-triazolo[4,3-a]pyridine ( 4d ) with potassium hydroxide yielded the 5-hydroxy/5-one system ( 4c or 6 ). Further reaction of 3a with bromine to give 3-bromo-5-chloro-s-triazolo-[4,3-a]pyridine ( 3g ) has provided the corresponding 3-cyano- and 3-carboxamido-5-chloro-s-triazolo[4,3-a]pyridine derivatives ( 3h and 3i ). Treatment of 6-chloro-2-hydrazinopyridine ( 1 ) with cyanogen bromide has provided 3-amino-5-chloro-s-triazolo[4,3-a]pyridine ( 3f ) which, with bromoacetaldehyde dimethyl acetal, transformed into 7-chloroimidazo[1,2-b]-s-triazolo[4,3-a]-pyridine ( 7 ). Finally, attempts at cyclizing N-oxalyl-N′-(6-chloropyrid-2-yl)hydrazine derivatives ( 2g-2i ) with intentions of preparing various 3-acyl-5-chloro-s-triazolo[4,3-a]pyridines for entry into other 3,5-disubstituted systems were unsuccessful.     

Synthetic Studies on Sialoglycoconjugates 89: Synthesis of Ganglioside GM3 and KDN-GM3 Containing Different Carbon-Chain Length Fatty Acyl Groups at the Ceramide Residue

ABSTRACT

Ganglioside GM₃ and KDN-ganglioside GM₃, containing hexanoyl, decanoyl, and hexadecanoyl groups at the ceramide moiety have been synthesized. Selective reduction of the azido group in O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)-O-(2,4-di-O-acetyl-6-O-benzoyl-β-D-galactopyranosyl)-(1→4)-O-(3-O-acetyl-2,6-di-O-benzoyl-β-D-glucopyranosyl)-(1→1)-(2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (1) and O-(methyl 4,5,7,8,9-penta-O-acetyl-3-deoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)-O-(2,4-di-O-acetyl-6-O-benzoyl-β-D-galactopyranosyl)-(1→4)-O-(3-O-acetyl-2,6-di-O-benzoyl-β-D-glucopyranosyl)-(1→1)-(2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (2), coupling with hexanoic, decanoic, and hexadecanoic acids, O-deacylation, and de-esterification gave the title gangliosides GM₃ (11→13) and KDN-GM₃ (14→16) in good yields. On the other hand, O-deacylation of 1 and subsequent de-esterification gave 2-azido-sphingosine containing-GM₃ analogue 17, which was converted into lyso-GM₃, in which no fatty acyl group was substituted at the sphingosine residue, by selective reduction of the azido group.     

Chemo‐Enzymatic Synthesis of 3‐Deoxy‐β‐D‐ribofuranosyl Purines

9‐(3‐Deoxy‐β‐D ‐erythro‐pentofuranosyl)‐2,6‐diaminopurine ( 6 ) was synthesized by an enzymatic transglycosylation of 2,6‐diaminopurine ( 2 ) with 3′‐deoxycytidine ( 1 ) as a donor of 3‐deoxy‐D ‐erythro‐pentofuranose moiety. This transformation comprises i) deamination of 1 to 3′‐deoxyuridine ( 3 ) under the action of whole cell (E. coli BM‐11) cytidine deaminase (CDase), ii) the phosphorolytic cleavage of 3 by uridine phosphorylase (UPase) giving rise to the formation of uracil ( 4 ) and 3‐deoxy‐α‐D ‐erythro‐pentofuranose‐1‐O‐phosphate ( 5 ), and iii) coupling of the latter with 2 catalyzed by whole cell (E. coli BMT‐4D/1A) purine nucleoside phosphorylase (PNPase). Deamination of 6 by adenosine deaminase (ADase) gave 3′‐deoxyguanosine ( 7 ). Treatment of 6 with NaNO₂ afforded 9‐(3‐deoxy‐β‐D ‐erythro‐pentofuranosyl)‐2‐amino‐6‐oxopurine (3′‐deoxyisoguanosine; 8 ). Schiemann reaction of 6 (HF/HBF₄+NaNO₂) gave 9‐(3‐deoxy‐β‐D ‐erythro‐pentofuranosyl)‐2‐fluoroadenine ( 9 ).     

Synthesis of β-（ 1→6）-Branched （ 1→3）-Glucononaoside with Alter-nate β- and α-Bonds in the Backbone

Lauryl glycoside of β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]α-D-Glcp-(1→3)-β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]α-D-Glcp-(1→3)-β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]β-D-Glcp was synthesized through 3 3 3 strategy. 3-O-Allyl-2,4,6-tri-O-benzoyl-β-D-glucopyranosyl-(1→3)- -[2, 3, 4, 6-tetra-O-benzoyl-β-D-glucopyranosyl-(1→6)-] 1,2-O-isopropylidene-α-D-glucofuranose was used as the key intermediate which was converted to the corresponding trisaccharide donor and acceptor readily.     

Synthese von N-Methyl- und N,N-Dimethylmerucathin sowie von N-Methyl- und N,N-Dimethylpseudomerucathin aus L-Alanin

Synthesis of N-Methyl- and N,N-Dimethylmerucathine and of N-Methyl- and N,N--Dimethylpseudomerucathine Starting from L -Alanine Starting form L -alanine, N-methylmerucathine (= (3R,4S)-4-(methylamino)1-phenyl-1-penten-3-ol; (3R,4S,)- 6 ), N,N-dimethylmerucathine (= (3R,4S)-4-(dimethylamino)-1-phenyl-1-penten-3-ol; (3R,4S)- 9 ), N-methylpseudomerucathine (= (3S,4S)-4-(methylamino)-1-phenyl-1-penten-3-01; (3S,4S)-6), and N,N-dimethylpseudomerucathine (= (3S,4S)-4-(dimethylamino)-1-phenyl-1-penten-3-ol; (3S,4S)- 9 ) were synthesized. The four compounds were analyzed by HPLC and compared with a natural khat extract.     

Synthesis of 4- and 5-(s-triazolo[4,3-b]pyridazinyl-3)-substituted cyclic polyols

4( R )-(6-Chloro-s-triazolo[4,3-b]pyridazinyl-3)-1,4-furanoses 10 and 11 , 5( R )-(6-chloro-s-triazolo[4,3-b]pyridazinyl-3)-1,5-pyranose 13 , and 2(S),3( R )-dihydro-5-(6-chloro-s-triazolo[4,3-b]pyridazinyl-3)-2,3-O-isopropylidenefuran ( 12 ) were prepared by cyclization of hydrazones 6–9 obtained from 6-chloro-3-hydrazinopyridazine ( 1 ) and aldofuranoses 2, 3 and 4 , and aldopyranose 5 .     

Triterpenoid Saponins from Schefflera arboricola

Four new triterpenoid saponins, named scheffarboside A – D ( 1 – 4 ), along with five known saponins were isolated from the stems of Schefflera arboricola. The structures of the four new saponins were determined as 3‐O‐(O‐β‐glucuronopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)oleanolic acid ( 1 ), 3‐O‐(O‐α‐arabinopyranosyl‐(1 → 4)‐O‐α‐arabinopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)oleanolic acid ( 2 ), 3‐O‐(O‐α‐arabinopyranosyl‐(1 → 4)‐O‐α‐arabinopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)hederagenin ( 3 ), 3‐O‐(O‐α‐arabinopyranosyl‐(1 → 4)‐O‐α‐arabinopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)oleanolic acid O‐α‐rhamnopyranosyl‐(1 → 4)‐O‐β‐glucopyranosyl‐(1 → 6)‐β‐glucopyranosylester ( 4 ), respectively, on the basis of spectroscopic and chemical degradation methods.     

Alkyl Rearrangement of Derivatives of 2-Anilino-4,6-dialkoxy-1,3,5-triazines in the Solid- and Liquid-state

Abstract

2-Anilino-4,6-dimethoxy-1,3,5-triazine (13), 2-anilino-4,6-diethoxy-1,3,5-triazine (14), 2-(2′-nitoanilino) 4,6-dimethoxy-1,3,5-triazine (15) undergo alkyl rearrangement in the liquid-state, while 2-(4′-nito-anilino) 4,6-dimethoxy-1,3,5-triazine (16) undergoes methyl rearrangement in the solid-state. The crystal structure and thermal behavior of these compounds are described. 13 crystallizes in monoclinic P2₁/c space group, a = 11.030(4), b = 6.345(4), c = 16.315(4) Å, β = 90.76(3)°. The calculated density for Z = 4 is 1.351 Mg/m³. The number of unique reflections collected is 2092, and the final R = 0.0643 [I > 2σ(I)]. 14 crystallizes in triclinic P-1 space group, a = 7.700(2), b = 9.723(3), c = 10.154(3) Å, α = 78.78(3), β = 70.32(3), γ = 73.67(3)°. The calculated density for Z = 2 is 1.266 Mg/m³. The number of unique reflections collected is 2401, and the final R = 0.0561 [I > 2σ(I)]. 15 crystallizes in monoclinic P21/m space group, a = 11.020(3), b = 6.600(2), c = 8.409(3) Å, β = 99.72(3)°. The calculated density for Z = 2 is 1.527 Mg/m³. The number of unique reflections collected is 1153, and the final R = 0.0502 [I > 2σ(I)]. 16 crystallizes in monoclinic P21/c space group, a = 7.499(3), b = 21.846(5), c = 7.895(3) Å, β = 115.42(3)°. The calculated density for Z = 4 is 1.576 Mg/m³. The number of unique reflections collected is 2036, and the final R = 0.0757 [I > 2σ(I)].     

Syntheses and Crystal Structures of the Novel Ternary Thioborates Na3BS3, K3BS3, and Rb3BS3

The orthothioborates Na₃BS₃, K₃BS₃ and Rb₃BS₃ were prepared from the metal sulfides, amorphous boron and sulfur in solid state reactions at temperatures between 923 and 973 K. In a systematic study on the structural cation influence on this type of ternary compounds, the crystal structures were determined by single crystal X‐ray diffraction experiments. Na₃BS₃ crystallizes in the monoclinic space group C2/c (No. 15) with a = 11.853(14) Å, b = 6.664(10) Å, c = 8.406(10) Å, β = 118.18(2)° and Z = 4. K₃BS₃ and Rb₃BS₃ are monoclinic, space group P2₁/c (No. 14) with a = 10.061(3) Å, b = 6.210(2) Å, c = 12.538(3) Å, β = 112.97(2) and a = 10.215(3) Å, b = 6.407(1) Å, c = 13.069(6) Å, β = 103.64(5)°, Z = 4. The potassium and rubidium compounds are not isotypic. All three compounds contain isolated [BS₃]^3– anions with boron in a trigonal‐planar coordination. The sodium cations in Na₃BS₃ are located between layers of orthothioborate anions, in the case of K₃BS₃ and Rb₃BS₃ stacks of [BS₃]^3– entities are connected via the corresponding cations. X‐ray powder patterns were measured and compared to calculated ones obtained from single crystal X‐ray structure determinations.     

A new hederagenin glycoside from <Emphasis Type="Italic">Nephelium lappaceum</Emphasis>

A new oleane-type triterpene oligoglycoside, hederagenin 3-O-(3-O-acetyl-β-D-xylopyranosyl)-(1→3)-α-L-arabinopyranoside (2), together with four known compounds, hederagenin (1), hederagenin 3-O-(4-O-acetyl-α-L-arabinopyranosyl)-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside (3), hederagenin 3-O-α-L-arabinopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside (4), hederagenin 3-O-β-D-glucopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→4)-β-D-xylopyranoside (5), was isolated from the hull of Nephelium lappaceum. All the isolates were obtained from the hull of rambutan for the first time.     

Adducts of Cyclodiphosph(V)azenes: Synthesis and Structure

The reaction of Ph₂PCl and PhPCl₂ with bis(trimethylsilyl)sulfur diimide in the presence of GaCl₃ and AlCl₃ yields diadducts of the corresponding cyclodiphosph(V)azene: [Ph₂PN]₂·(GaCl₃)₂ ( 1 ), [Ph₂PN]₂·(AlCl₃)₂ ( 2 ), and [Ph(Cl)PN]₂·(AlCl₃)₂ ( 3 ). This reaction is triggered by Lewis acids, which catalyse the (CH₃)₃Si‐Cl and S₈ elimination. The structures of 1· 2 CH₂Cl₂, 2· 2 CH₂Cl₂ and 3 were determined by single crystal X‐ray studies ( 1 : triclinic, , a = 9.679(2) Å, b = 9.863(2) Å, c = 11.366(2) Å, α = 113.55(3)°; β = 99.59(3)°; γ = 106.67(3)°; V = 902.8(3) ų, Z = 1; 2 : triclinic, , a = 9.639(2) Å, b = 9.804(2) Å, c = 11.321(2) Å, α = 113.71(3)°; β = 99.44(3)°; γ = 106.70(3)°; V = 889.3(3) ų, Z = 1; 3 : orthorhombic, Pbca, a = 14.853(3) Å, b = 9.261(2) Å, c = 16.631(3) Å, V = 2287.7(8) ų, Z = 4.     

Enzyme-Mediated Preparation of the Single Enantiomers of the Olfactory Active Components of the Woody Odorant Timberol®

Enantiomerically pure (3S)- 3a and - 3b , the olfactory active forms of 1-(2,2,6-trimethylcyclohexyl)hexan- 3-ol, components of the commercial woody odorant Timberol ^®, are obtained by lipase-PS-mediated enantioselective acetylation of the allylic alcohols 6 and 7 and of the saturated alcohol 3 . These materials, as mixtures of diastereoisomers, provided (3R)-configured transformation products. However, whereas in the conversion of 6 and 7 there is no diastereoselection, 3 provided the acetate of (1′S,3R,6′R)- 3c much more rapidly than that of the diastereoisomer (1′R,3R,6′S)- 3d (Scheme 3). Inversion of the configuration at C(3) of the side chain of the olfactory inactive (3R)-materials obtained as acetates in the enzymic treatment of 6 , 7 , and 3 also provided, eventually, the desired olfactory active (3S)-products.     

Herstellung enantiomerenreiner Derivate von 3-Amino- und 3-Mercaptobuttersäure durch SN2-Ringöffnung des β-Lactons und eines 1,3-Dixoanons aus der 3-Hydroxybuttersä ure

Preparation of Enantiomerically Pure Derivatives of 3-Amino- and 3-Mercaptobutanoic Acid by S_N2 Ring Opening of the β-Lactone and a 1,3-Dioxanone Derived from 3-Hydroxybutanoic Acid From (S)-4-methyloxetan-2-one ( 1 ), the β-butyrolactone readily available from the biopolymer ( R )-polyhydroxybutyrate (PHB) and various C, N, O and S nucleophiles, the following compounds are prepared:(s)-2-hydroxy-4-octanone ( 3 ), (R)-3-aminobutanoic acid ( 7 ) and its N-benzyl derivative 5 , (R)-3-azidobutanoic acid ( 6 ) (R)-3-mercaptobutanoic acid ( 10 ), (R)-3-(phenylthio)butanoic acid ( 8 ) and its sulfoxide 9 . The (6R)-2,6-dimethyl-2-ethoxy-1,3-dioxan-4-one ( 4 ) from (R)-3-hydroxybutanoic acid undergoes S^N2 ring opening with benzylamine to give the N-benzyl derivative (ent- 5 ) of (S)-3-aminobutanoic acid in 30?40% yield.     

Synthesis and Characterization of Three Homoleptic Bismuth Silanolates: [Bi(OSiR3)3] (R = Me,Et, iPr)

The bismuth tris(triorganosilanolates) [Bi(OSiR₃)₃] ( 1 , R = Me; 2 , R = Et; 3 , R = iPr) were prepared by reaction of R₃SiOH with [Bi(OtBu)₃]. Compound 1 crystallizes in the triclinic space group with Z = 2 and the lattice constants a = 10.323(1) Å, b = 13.805(1) Å, c = 21.096(1) Å and α = 91.871(4)°, β = 94.639(3)°, γ = 110.802(3)°. In the solid state compound 1 is a trimer as result of weak intermolecular bismuth‐oxygen interactions with Bi–O distances in the range 2.686(6)–3.227(3) Å. The coordination at the bismuth atoms Bi(1) and Bi(3) is best described as 3 + 2 coordination whereas Bi(2) shows a 3 + 3 coordination. The intramolecular Bi–O distances fall in the range 2.041(3)–2.119(3) Å. Compound 3 crystallizes in the orthorhombic space group Pbcm with Z = 4 and the lattice constants a = 7.201(1) Å, b = 23.367(5) Å and c = 20.893(1) Å, whereas the triethylsilyl‐derivative 2 is liquid. In contrast to [Bi(OSiMe₃)₃] ( 1 ) compound 3 is monomeric in the solid state, but shows similar intramolecular Bi–O distances in the range 1.998(2)–2.065(5) Å. The bismuth silanolates are highly soluble in common organic solvents and strongly moisture sensitive. Compound 1 shows the lowest thermal stability.