Isothiocyanates reaction with alcohols

The isothiocyanates are transformed into thiocarbamates by reaction with alcohols or into the acetamides by reaction with acetic acid or anhydride and sodium acetate. These transformations have also been applied to the preparation of unsaturated aminosugars73,74. Thus, suprafa-cial rearrangement of ethyl 2.3,4-trideoxy-6-0-methanesulfonyl-4-thiocyan ato-a-D-t/ireo-hex-2-enopyranoside to the 2-isothiocyanatc occurs in refluxing toluene (1 h), whereas the erythro-epimer needs to be heated in dimethylformamide for 6 hours73. This difference in reactivity might be due to an unfavorable anomeric effect and C-6 in an axial orientation in the transition state of the errr/iro-epimer, respectively. 

Thiophosgene reacts with alcohols and phenols to form chlorothionoformates or thiocarbonates. The most studied reactions of thiophosgene are with primary amines to give isothiocyanates and with secondary amines to give thiocarbamyl chlorides ... 

Several examples of the binding of enzymes to poly(vinyl alcohol) are in the literature. These could possibly be used to treat enzyme deficiency diseases. In a recent example, trypsin was immobilized on poly(vinyl alcohol) fibers using maleic dialdehyde or bromal. While the reaction was more complete with bromal, the reaction with maleic dialdehyde gave a better support which showed decreasing activity with increasing enzyme content. The activity of the bromal activated system was independant of the enzyme content (52 ). Trypsin and papain were attached to poly(vinyl alcohol) by the reaction sequence shown in Equation 13. In this case, the crosslinked poly(vinyl alcohol) is treated by the 1,3-dioxalone derivative and then converted to either the isothiocyanate or the diazonium salt for coupling with the enzyme. The bound enzymes showed significant, altho reduced, activity in each case (53). 

N-Bromoiraides, 46, 88 />-Bromophenyl isothiocyanate, 46, 21 Butadiene, 46, 106 Butadiyne, diphenyl, 46, 39 A -Butenolide, 46, 22 i-Butyl alcohol in synthesis of phenyl 1-butyl ether, 46, 89 1-Butyl azidoacetate, 46, 47 hydrogenation of, 46, 47 1-Butyl chloroacetate, reaction with sodium azide, 45, 47 i-Butyl hypochlorite, reaction with cy-clohexylamine, 46,17 1-Butylthiourea, 46, 72 1-Butylurea, 46, 72... 

This method was extensively reviewed in <84CHEC-I(4)545> and a brief summary is presented here interestingly, since the mid-1980s, this reaction has become less popular. A(-Aryl benzhydrazonyl chlorides react with thiobenzamides to form trisubstituted thiadiazolines which on treatment with alcohols furnish the 2-alkoxy derivative (Scheme 25). A-Arylbenzhydrazonyl chlorides also react with thioketenes to yield 5-methylene thiadiazolines (Equation (16)). Other examples involve the addition of the nitrileimine generated from A-trifluoroacetobenzhydrazonyl bromide to the 0=S of potassium isothiocyanate and methyl isocyanate <87JHC1391>. 

Although very little is known for the reactions of isolated germylenes 146, 147, and 148, diarylgermylene (150) was found to undergo a variety of reactions with olefins, dienes, acetylenes, alcohols, isothiocyanates, elemental chalcogens, and hydrosilanes as in the cases of less hindered, transient germylenes previously reported. 

Zirconium and hafnium dialkylamides are highly reactive compounds. They undergo (i) protolytic substitution reactions with reagents such as alcohols, cyclopentadiene and bisftrimethylsilyOamine 63 64 (ii) insertion reactions with C02, CS2, COS, nitriles, phenyl isocyanate, methyl isothiocyanate, carbodiimides and dimethyl acetylenedicarboxylate 69-72 and (iii) addition reactions with metal carbonyls.73 These reactions are summarized with reference to Zr(NMe2)4 in Scheme 1. 

One of the most commonly used class of derivatization agents for diasteromer formation are isothiocyanates and isocyanates. Enantiomers of /3-blockers, amphetamine, epinephrine, methamphetamine, and mexiletine have been resolved after derivatization with these agents. Isothiocyanates produce thiourea derivatives upon reaction with primary and secondary amines. Thiourea derivatives also provide a strong UV absorbance for the detection of enantiomers lacking a strong UV chromophore. Isocyanates produce ureas when reacted with amines. The physical properties of these ureas are similar to thiourea derivatives. Isocyanates will also react with alcohols to yield carbamates. 

The isocyanate, SF5NCO, is easily hydrolyzed to SF5NH2 and C02, whereas SF5NCS is hydrolytically very stable. Both compounds undergo addition reactions with substrates containing easily replaceable hydrogen atoms, i.e., alcohols, thiols, and amines. With alcohols (thiols) the isocyanate and isothiocyanate give urethanes and thiourethanes, respectively. 

SODIUM ISOTHIOCYANATE (540-72-7) Exposure to light causes slow decomposition, forming cyanide, sulfur oxides, and nitrous vapors. Violent reaction with organic peroxides, nitric acid. Incompatible with acids, bases, chlorates, ammonia, amines, amides, alcohols, glycols, caprolactam, nitrates, peroxides, potassium chlorate, potassium iodate, silver nitrate, sodium chlorate. Forms explosive mixture with sodium nitrate. 

Compound 190 (R = PhNH) was also obtained by treatment of the corresponding anthranilic acid derivative 189 with hydrogen chloride in ether (2.25 h), with potassium isothiocyanate in aqueous alcohol (20°C, 12 h), and treatment of the reaction mixture at 110-112°C for 1.5 h [114],... 

Isomannide (80) was the core for a hexahydrofurofuran library." Primary amines were loaded onto solid-support by reductive amination and acylated with bromoacetic acid to give bromides 79 (Scheme 7.16). Alkylation of bromides 79 on solid-support with isomannide (80) gave the solid-supported alcohols 81. A Mitsunobu reaction with phthalimide (82) proceeded to furnish amines 83 in excellent yield and purity after removal of the protecting group." " Support-bound primary amines 83 were converted to secondary amines by stepwise imine formation with aldehydes 84 and reduction with sodium borohydride." The hindered secondary amines 85 were acylated with acid chlorides, sulfonyl chlorides, isocyanates, and isothiocyanates to yield 87 after cleavage from solid-support. 

Functionalized terpyridines can be created to contain a variety of binding and catalytic functional groups (15). Bromomethyl derivatives can be reacted with the sodium salts of alcohols to form ethers, or reacted with the sodium salts of amines to form substituted amines. Each sodium salt was formed by reaction with sodium hydride. Gabriel synthesis leads to the creation of an aminomethyl derivative, which can be converted into amide with acyl chlorides, ureas with isocyanates, or thioureas with isothiocyanates. Terpyridine-5-carboxylic acid is converted to the acyl chloride with thionyl chloride and can be coupled with a variety of amines to form amide derivatives. 

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