Cyanohydrin sulfonates

Kinetic Resolution by Transesterification. Asymmetric transformation involving acylation of chiral alcohols is by far the most common example of kinetic resolution by lipase-catalyzed transesterification, most commonly with irreversible vinyl esters. This field is now becoming the most widely applied technique involving lipases. Recent reports of the numerous secondary alcohol substrates include various monocyclic (eq 6) andacyclic compounds, cyanohydrins, sulfones, and glycals, to name a few. 

Aminoenol sulfonates Cyanohydrin sulfonates N-Sulfenylcarbamic carboxylic anhydrides... 

DiaminO 4,4-dimethyl-l,3,5-thiadiazine hydrobromide was isolated as by-product (418). Benzene sulfonates of cyanohydrin prepared from sodium cyanide and an halobenzoaldehyde, when treated with thiourea or its derivatives, afford 2,4-diamino-5-(p-halogenophenyl)-thiazole benzene sulfonates (447). Similarly, cyanoamido thiocarbamates obtained from cyanamide and isothiocyanates yield substituted 2,4-diaminothiazoles (598). 

Besides acylation and alkylation reactions, typical carbonyl reactions, such as reduction and substitution, are known. Thus, the oxo group in position 3 of 8 is attacked by sodium cyanide, resulting in the cyanohydrin in 55% yield. Subsequent dehydration with p-toluene-sulfonic acid and acetylation in position 5 gives 1-benzothiepin 12.90... 

Beau and Sinay described a method which laid the groundwork for cyanohydrin acetonide alkylations [1]. Their strategy involved alkylation and reductive desulfonylation of glucopyranosyl sulfones 4. In this one-pot procedure, low temperature alkylation and subsequent reductive desulfonylation with lithium naphthalenide generated -C-glycosides with good selectivity >10 1 j3 a) and in moderate to good yield (Eq. 1). 

Scheme 3.23 Asymmetric Strecker synthesis using a-amido sulfones with acetone cyanohydrin.

Cyanoamido-thiocarbamates, from cyan-amide and isothiocyanates, 297 Cyanohydrin, benzene sulfonates, synthesis of, from sodium cyanide and haJo-benzaldehyde, 297... 

An interesting variant of these Michael-type additions is the 1,6-addition of the anion of type (29) to a dienyl sulfone as a route to tagetones and 1,4-addition to nitrostyrene to form 3-nitro ketones. A key step in a synthesis of 11-deoxyanthracyclinone involves the regioselective reaction of complexed styrene with lithiated protected acetddehyde cyanohydrin. ... 

Recently, the group of Herrera, Bernardi, and Ricci realized the enantioselective synthesis of protected a-amino nitriles from the corresponding a-amino sulfones 137, which act as effective precursors for the in situ generation of imines, by the use of acetone cyanohydrin (138) as a cyanide source using quinine-derived PTC 136 [64]. The aminonitriles 139 were produced with broad generality in 50-88% ee (Scheme 8.53). However, a similar protocol using KCN and TMSCN resulted in a lower ee value. 

The reactions of enolized keto carboxylic esters with ammonia and amines are described on page 507, and those of a-amino alcohols, cyanohydrins, and a-hydroxy sulfonic acids on pages 516-520. 

Reduction-decyanation. wc-Cyanohydrins can be converted to alkenes by conversion to a methylthiomethyl ether followed by oxidation to the sulfone. Reduction of this derivative with sodium naphthalenide results in an alkene... 

Ammonium acetate Aniline Benzanthrone Bromine Carmine (Coccus cacti) Carminic acid 2-Chlorophenol Crystal violet lactone Diaminodiphenic acid Di-n-amylamine Diazoaminobenzene o,a-Dichlorotoluene Dimethoxypropane 4-Dimethylaminoazobenzene-4-sulfonic acid, sodium salt p-Dimethylaminobenzaldehyde 4-Dimethylaminobenzene 6-Dimethylaminophenylazobenzothiazole N,N-Dimethylaniline Dinitrotoluene 2,4-Dinitrotoluene Direct blue 8 Direct blue 10 Direct blue 25 Direct blue 218 Direct orange 6 Direct violet 32 Disperse blue 7 Disperse red 60 Dodecene-1 N-(p-Ethoxycarbonylphenyl)-N -ethyl-N -phenylformamidine Ethylene cyanohydrin Ethylene thiourea... 

Aminoenol sulfonates Cyanohydrin -N-Sulfenylcarbamic carboxylic anhydrides N-Sulfinyldicarboxylic acid imides... 

Recently, several other aminopolymers were synthesized for the NCA polymerization. Ichie and coworkers used copolymers of styrene-vinyl benzylamine and methyl methacrylate-vinyl benzylamine for NCA polymerization to study the kinetics of NCA polymerization with macroinitiators. 2 The polymerization was Ist-order with respect to monomer concentration and was much faster in nitrobenzene than in dioxane or THF. Kiba patented a new system for NCA polymerization with the different aminopolymers [38] produced according to Scheme 5. He also claimed the ester exchange reaction of the resulting graft copolymer with ethylene cyanohydrin over p-toluene sulfonic acid. 

A similar concept of was pursued by the Ricci group [45], The hydrocyanation of ahphatic N-Boc a-amido sulfones 80 was accompHshed with the cinchona-derived quaternary ammonium salt 82 (Scheme 30.19). Here, acetone cyanohydrin 81 was employed as cyanide source that is cheap, has good solubility in organic solvents, and is available on a large scale. (S)-Configurated primary, secondary, and tertiary aliphatic N-Boc a-amino nitriles 83 were obtained in high yields (85-95%), but enantioselectivities were lower (50-88% ee) in comparison to Ooi s protocol [43, 44]. 

Herrera RP, Sgarzani V, Bernard L, Fini F, Pettersen D, Ricci A. Phase transfer catalyzed enantioselective Strecker reactions of a-amido sulfones with cyanohydrins. J. Org. Chem. 2006 71 9869-9872. 

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