Vinylamines synthesis

Enamines are the stable products of a similar reaction between secondary amines (such as pyrrolidine or morpholine) and aldehydes and ketones.218 These vinylamines are reactive reagents of value in synthesis they function as specific enol equivalents of carbonyl compounds, readily undergoing alkylation and acylation processes (e.g. Section 5.9.2, p. 632). 

Open-chain vinylamine is an identifiable side product during synthesis of 1,4,7-triazacyclononanes, resulting from the side FL -elimination process. Intermediate 82 can be isolated by column chromatography on neutral alumina and subsequently converted to 2-methyl-l,6-ditosyl-l,3,6-triazocane 31 by the addition of either silica gel or HBF4. The reaction also proceeds smoothly under Lewis acid catalysis using BF3 etherate (Equation 9 <1999TL9363>). 

The cycloaddition of l-methoxy-3-trimethylsilyoxy-1,3-butadiene with 3-methyl-1,2-benziso-thiazole 1,1-dioxide (107) (R = Me) affords the pyridone (108) <84H(22)67l>. An improved synthesis of 1,2-benzisothiazole 1,1-dioxide has led to the preparation of the benzothiazepine (109) (R = H) by cycloaddition of the ynamine followed by ring expansion <83CC520>. Addition of yV,7V-diaikylprop-l-ynamines to 3-substituted 1,2-benzisothiazole 1,1-dioxide (107) (R = SMe, SPh, SePh) gives mainly the imine-vinylamine (110) with only small amounts of the benzothiazepine (109) <85CC845>. 

Synthesis of a-Imidostyrenes. a-Imidostyrenes, useful precursors to vinylamines can be synthesized by introducing an imido group to the a-position of styrenes with the diphenyl sulfoxide-Tf2 O reagent combination. Styrenes with a hydrogen atom at the a-position react with diphenyl(trifluoromethanesulfonyloxy)sulf-onuim triflate to form diphenylstyrylsuifonium triflates which, in turn are converted into the corresponding a-imidostyrenes on treatment with sodium or potassium salts of cyclic imides (eq 9). 

The HR using sodium hypochlorite has been applied to a synthesis of a key intermediate for a route to (+)-biotin, and sodium hypochlorite also finds use in the preparation and HR of A, A -dichlorocarboxamide sugars. The sodium hypochlorite variation of the HR has been extensively used to prepare poly(vinylamine) from polyacrylamide and related polymers. One final application of sodium hypochlorite in a HR is the synthesis of glycoside hydrolase inhibitor 99. ... 

An improved method that can be easily scaled-up has been developed for the preparation of benzyl-N-vinyl carbamate 810 (Z-vinylamine), a valuable synthetic intermediate in the synthesis of p-lactam antibiotics [589]. In this method, vinyl isocyanate 809, formed by the Curtius rearrangement of acryloyl azide 808, is codistilled with a solvent such as toluene into benzyl alcohol containing a catalyst and an inhibitor. The product thus obtained can be purified by crystallization, thereby avoiding purification by high-vacuum distillation or chromatography. Potential safety issues associated with the process are important [590, 591]. 

SYNTHESIS OF VINYLAMINES AND RELATED COMPOUNDS THROUGH NITROGEN-CARBON(sp ) BOND-FORMING REACTIONS... 

---