Structure of de-o-acylated lipopolysaccharide from the escherichia coli re mutant strain F 515

The structure of the oligosaccharide portion of an $\text{E.coli}$ Re lipopolysaccharide was determined as α-KDO-(2→4)-α-KDO-(2→6)-β-GlcN-α(1→6)-α-GlcN, bisphosphorylated at positions 1 and 4′. Taking into account the previous determination of the acylation pattern of the GlcN disaccharide, the total structure of $\text{E.coli}$ Re LPS was thus established.     

Stekeospecific transformation of D-sugar to L-sugar in complex aminoglycoside. Synthesis of a kanamycin B analog having 2,6-diamino-2,4,6-trideoxy-L-arabino-hexopyranose

A 4′-ene derivative of kanamycin B ($\text{4}$) was derived from the epoxide ($\text{1}$) by oxidative elimination of the 4′-phenylseleno group into the allylic alcohol ($\text{3}$). The title compound, 0-(2,6-diamino-2,4,6-trideoxy-β-L-arabino-hexopyranosyl)-(1→4)-0-[3-amino-3-deoxy-α-D-glucopyranosyl-(1→6)]-2-deoxystreptamine ($\text{6}$) was obtained from $\text{4}$ by stereospecific hydrogenation followed by removal of the masking groups, changing the D-sugar moiety of the 4-0-glycoside portion into an L-sugar.     

Zur struktur der 3-desoxyoctulosonsäure- (KDO-) region des lipopolysaccharids von Salmonella minnesota Re 595

Spectroscopic data (¹H- and ¹³C-N.m.r.) indicate that the tetrasaccharide αdOclA$\text{p}$(2→4)αdOclA$\text{p}$(2→6)βGIcN$\text{p}$(1→6)GlcN is formed upon hydrazinolysis of the lipopolysaccharide from $\text{Salmonella minnesota}$ Re 595.     

Triterpene glycosides of Hedera taurica

From the leaves of Crimean ivy we have isolated the previously known glycosides 3-O-α-L-Ara_p-28-O-[O-α-L-Rha_p-(1→4)-O-β-D-Glc_p-(1→6)-β-D-Glc_p]hederagenin, 3-O-[O-α-L-Rha_p-(1→2)-α-L-Ara_p]-28-O-[O-α-L-Rha_p-(1→4)-O-β-D-Glc_p-(1→6)-β-D-Glc_p]oleanic acid and -hederagenin, and 3-O-[O-α-L-Rha_p-(1→2)-α-L-Ara_p]-28-O-[O-β-D-Glc_p-(1→6)-β-D-Glc_p]hederagenin and a new one: tauroside H₁ — 3-O-[O-α-L-Rha_p-(1→2)-O-α-L-Ara_p]-28-O-[O-α-L-Rha_p-(1→4)-O-β-D-Glc_p-(1→6)-β-D-Glc_p]echinocystic acid.     

Synthese von oligosaccharid-determinanten des T-antigens mit amid-spacer zur darstellung synthetischer antigene

The β (1 → 3) -linked disaccharide $\text{1}$$\text{5}$ was synthesized from $\text{D}$-galactose and a $\text{D}$-galactosamine unit with a watersoluble amide spacer. This represents the hapten of T-antigen and, when coupled to a protein, is suitable for use as an artificial antigen. Other O-β-$\text{D}$-galactosylated derivatives of galactosamine were synthesized.     

Studies on the stereochemical course of intramolecular cycloaddition reactions of olefinic o-quinodimethanes-stereoselective synthesis of 8α, 9α, 14β-estranes

The stereoselective synthesis of 3-O-methyl-7α-$\text{p}$-toluenesulphonyl-8α, 9α, 14β-estradiol ($\text{25}$) and its 11-oxo derivative ($\text{26}$) $\text{via}$ thermolysis of 1β-$\text{tert}$-butoxy-2α-[2-(4-methoxybenzocyclobutenyl)ethyl]-2β-methy1-3α-[2-($\text{p}$-toluenesulphonyl)ethenyl] cyclopentane ($\text{22}$) and its oxo derivative ($\text{24}$), which were derived from condensation product ($\text{9}$) of optically active aldehyde ($\text{8}$) and 1-cyano-4-methoxybenzocyclobutene through $\text{10}$ and $\text{11}$ to selenides $\text{16}$ and $\text{21}$, is described.     

A case of oligomerization on attempted chlorination of an α-hydroxy acetal with the triphenylphosphine tetrachloromethane reagent

Treatment of methyl 3,5-dideoxy-β-$\text{D}$-$\text{erythro}$-pentofuranoside $\text{8}$ with the Ph₃P-CCl₄ reagent gave none of the expected 2-chloro derivative but a mixture of l→2 linked oligosaccharides, $\text{9}$, $\text{10}$ with some higher homologues, terminated by αa 2-chloro-2,3,5-trideoxy-α-$\text{D}$-$\text{threo}$-pentofuranosyl unit at the non reducing end.     

Thermal rearrangement of divinylcyclopropane systems. Preparation of functionalized,stereochemically defined bicyclic and tricyclic products containing the bicyclo[3.2.1]octane skeleton

A study involving the preparation and thermolysis of substituted 6-$\text{exo}$-(1-alkenyl)bicyclo[3.1.0]hex-2-ene systems (14, 15, 23, 29, 40) shows (a) that C-8 functionalized bicyclo[3.2.1]octa-2,6-dienes can be prepared readily $\text{via}$ this methodology (14 → 16; 15 → 17), (b) that the rearrangement reaction is stereospecific even when the 6-(1-alkenyl) group is substituted with a sterically bulky isopropyl group (23 → 24; 29 → 30), and (c) that the method can be extended to include the preparation of tricyclic systems (40 → 41).     

A novel synthesis of carbacyclin analogs via a stereoselective introduction of 15α-hydroxy group

(+/-)-6,9α-Methanoprostaglandin I₃, ($\text{2}$) and (+/-)-5,6-dihydro-6,9α-methano-6β-prostaglandin I₃, ($\text{4a}$) have been synthesized using a new method for the stereoselective introduction of the 15α-hydroxy group via a stereoselective electrophilic addition of phenyl-sulfenyl chloride to the enol ether ($\text{6}$) and ($\text{23}$) respectively.     

Circular dichroism of α-deuteriocarboxylic acids. Dissignate behavior of deuterium.

Positive n → π^* Cotton effects were shown by ($\text{S}$-2-deuteriopropionic acid, ($\text{S}$)-2-deuteriosuccinic acid, ($\text{R}$)-2-deuterioglycine and ($\text{R}$)-2-deuterioglycolic acid. Using an octant projection and conformational and chiroptical data, it can be shown that the deuterium substituent makes a dissignate contribution to the Cotton effect.     

Chemical synthesis of phosphorylated fundamental structure of lipid a

1-α-Monophosphate ($\text{2}$), 4′-monophosphate ($\text{3}$), and 1-α, 4′-diphosphate ($\text{4}$) of 6-0-(2-deoxy-2-tetradecanoylamino-6-0-tetradecanoyl-β-D-glucopyranosyl) -2-deoxy-2-tetradecanoylamino-3, 4-di -0-tetradecanoyl-D-glucopyranose were prepared in order to elucidate the role of phosphate moieties in endotoxic activity of lipid A.     

Synthesis of 7-thiologibberellin A3 and A1 and their photochemical ring closure to 7→15α-thiololactones

The thiogibberellin analogs $\text{3}$ and $\text{4}$ were synthesized via sulfhysdrolysis of the carboxylic acid anhydrides $\text{1}$ and $\text{2}$ and transformed photochemically to the corresponding 7→15α-thiololactones $\text{5}$ and $\text{6}$.     

An efficient method for selective amino acid protection of meso-2,2′-diaminodicarboxylic acid: An improved synthesis of FK-156

An efficient method for selective amino acid protection with proper differentiation between the two amino acid groups in meso-2,2′-diaminopimelic acid has been achieved [$\text{7}$ → $\text{8}$ → $\text{9}$ → $\text{10}$ → $\text{11}$] and applied to the synthesis of FK-156 [$\text{10}$ → $\text{12}$ → $\text{14}$ → $\text{1}$].     

Pummerer reaction intermediate as an initiating function for cationic olefin cyclization

Treatment of N-(2-methyl-2-propenyl)-N-methyl-α-(methylsulfinyl)acetamide ($\text{6a}$) with trifluoroacetic anhydride caused the cationic olefin cyclization through a Pummerer reaction intermediate to give the six-membered lactams $\text{7}$ and $\text{8}$. Similar reaction converted N-2-butenyl-N-methyl-a-(methylsulfinyl)acetamide ($\text{6b}$) to the five-membered lactam $\text{9}$, and N-2-propenyl-N-methyl-α-(methylsulfinyl)- acetamide ($\text{6c}$) to the five-membered lactams $\text{11}$ and $\text{12}$.     

Cyanosugars III : The reaction of trimethylsilyl cyanide with keto,epoxy and acetal derivatives of carbohydrates

Reaction of methyl 2-acetamido-4,6-$\text{O}$-benzylidene-2-deoxy-α-$\text{D}$-$\text{ribo}$-hexopyranosid-3-ulose with Me₃SiCN afforded methyl 2-acetamido-4,6-$\text{O}$-benzylidene-3-$\text{C}$-cyano-2-deoxy-3-$\text{O}$-trimethylsilyl-α-$\text{D}$-$\text{allo}$- Reaction of ethyl 4,6-di-$\text{O}$-acetyl-2,3-anhydro-α-$\text{D}$-mannopyranoside with Me₃SiCN gave the corresponding ethyl 4,6-di-$\text{O}$-acetyl-2-$\text{C}$-cyano-2-deoxy-α-$\text{D}$-glucopyranoside. Reaction of methyl 4,6-$\text{O}$-benzylidene-2,3-anhydro-α-$\text{D}$-allopyranoside or methyl 4,6-$\text{O}$-benzylidene-2,3-di-$\text{O}$-tosyl-α-$\text{D}$-glucopyranoside with Me₃SiCN at - 75° or - 50° gave the corresponding methyl 6-$\text{O}$-[(R)-cyano phenyl methyl]-α-$\text{D}$-glyco-pyranosides with high or total regio and stereoselectivity.     

Synthesis with immobilized enzymes of two trisaccharides,one of them active as the determinant of a stage antigen.

Glycosidation of disaccharides I and III with a system of five immobilized enzymes gave excellent yields of trisaccharides $\text{β-D}$-Gal-(1→4)-$\text{β-D}$-GlcNAc-(1→6)-$\text{D}$-Gal ¦ the I(Ma) determinant ¦ and $\text{β-D}$-Gal-(1→4)-$\text{β-D}$-Glc-NAc-(1→3)-$\text{D}$-Gal, on the milimole scale.     

Intramolecular diels-alder reaction with furan-diene: Total synthesis of (±)-11-ketotestosterone and (±)-adrenosterone

A novel D → BCD → ABCD route to 11 -keto steroids is reported involving a high yield stereoselective intramolecular Diels-Alder reaction of furan-diene $\text{12}$ in water as a key-step. The dienophilic side chain is readily introduced starting from $\text{8}$ via a sequence involving alkylation with ethyl ($\text{E}$)-3-ethoxy-4-iodo-2-butenoate, reduction and acid hydrolysis. The reduced adduct $\text{14}$ is further converted into (±)-adrenosterone ($\text{6}$) via $\text{24}$, the dienediolate equivalent of which is a known intermediate in corticosteroid synthesis.     

A synthetic approach to (+)-aldosterone and its relatives (2)- a stereoselective synthesis of (+)-trans-4,5-(4-methoxybenzo)- 1β , 7aβ - ( 2α-methoxymethyl- 5 -oxofuro) hydrindane

A stereoselectivity in an intramolecular cycloaddition of the olefinic $\text{o}$-quinodimethanes 13 and 23 generated $\text{in}$$\text{situ}$ from the thermolysis of optically active 4β-[2-(4-methoxybenzocyclobutenyl)ethyl] -5α-methoxymethyl-3-phenyl-thio-methylenefuran-2-ones 12 and 22, respectively, is studied and a stereoselective synthesis of (+)-$\text{trans}$-4,5-( 4-methoxybenzo) -1β,7aβ-(2α-methoxymethyl-5-oxofuro)hydrindane 1 is also described.     

A new steroidal lactone with plant growth-regulatory activity from dolichoslablab seed

A new plant growth-promoting sterol was isolated from immature seeds of $\text{Dolichos}$$\text{labla}$. The structure was elucidated as (22$\text{R}$, 23$\text{R}$-2α, 3α, 22, 23-tetrahydroxy-B-homo-7-oxa-5α-ergost-24(28)-en-6-one $\text{1}$.     

On the question of carbonyl oxide intermediates in the oxygen transfer by furan endoperoxides and bicyclic ozonides: intramolecular trapping experiments

On heating the furan endoperoxide ($\text{2}$) rearranges into the enol ester ($\text{4}$) and the bicyclic ozonide ($\text{3}$) affords instead the rearranged ozonide ($\text{7}$). The process ($\text{2}$) → ($\text{4}$) represents an intramolecular Baeyer-Villiger rearrangement presumably via the dioxirane (D-2), while the process ($\text{3}$) → ($\text{7}$) represents intramolecular trapping of the carbonyl oxide (C-3).