Aldehydes, reaction with amines

Figure 1.105 Glutaraldehyde can undergo complex reactions with amine groups, resulting in aldehyde-containing derivatives that can be used in conjugation reactions.

Aldehyde particles are spontaneously reactive with hydrazine or hydrazide derivatives, forming hydrazone linkages upon Schiff base formation. Reactions with amine-containing molecules, such as proteins, can be done through a reductive amination process using sodium cyanoborohydride (Figure 14.21). 

Benzotriazol-l-yl)methyl]triphenylphosphonium chloride 848 reacts with BunLi and aldehydes to give l-(alken-l-yl)benzotriazoles 849. Addition of bromine to the double bond of derivatives 849 followed by a reaction with amines furnishes amides 850. A variety of primary or secondary amines can be used. This way aldehydes are conveniently homologated and converted to amides with a one-atom longer chain (Scheme 136) <2004ARK(ix)44. 

The aldehyde moiety of 50 can be condensed with either amines or active methylene compounds. In the case of reactions with amines, the aldehyde 50 (presumably obtained by reduction of the cyano group with diisobutyl-aluminium hydride (DIBAL-H)) forms simple Schiff bases 51 (Equation 20) <1998J(P1)3557>. 

Note For A% yields x/y The first yield x represents that for reactions with A-Boc anthranilic acid, 13. The second yield y represents that for A-Me-Boc anthranilic acid, 14. Row 27 represents yields of reactions with aldehyde 27. Column 15 represents yields of reactions with amine 15. 

Exchange reactions with amines and thiols (X = N, S in Fig. 156) are the most studied (see below) however, interesting C-alkylations, - based on the rather unusual replacement by bis-aldehyde (402, Fig. 157) to give poly( 5-diketone)s 403, have also been performed. 

Properties Yellow crystals or light-yellow liquid mild odor. Mp 15C, bp 51C, d 1.14 (20/20C), bulkd 10.0 lb/gal (20C), vapor has a green color and burns with a violet flame, refr index 1.3826 (20C). Polymerizes on standing or in presence of a trace of water. An aqueous solution contains monomolecu-lar glyoxal and reacts weakly to acid. Undergoes many addition and condensation reactions with amines, amides, aldehydes and hydroxyl-containing materials. Glyoxal VP resists discoloration. 

Carbonyl difluoride is a particularly versatile fluorinating agent, and an important material for the synthesis of organofluorine compounds [1079], Its reactions with perfluoroalkenes gives perfluoroacyl fluorides in the presence of a fluoride ion source, and its facile reaction with amines or alcohols results in the formation of carbamoyl fluorides or fluoroformates, respectively. The fluorination of carbonyl compounds, such as aldehydes and ketones, with COF can give gem-difluorides by replacement of the carbonyl oxygen atom with two atoms of fluorine e.g.-. 

The periodate oxidation of 165 and its derivatives gave 195, which could be transformed into a variety of derivatives (194 and 196) (80MI8) upon reaction with amines, hydrazines, semicarbazide, or thiosemicarbazide (Scheme 44). The thiosemicarbazones 196 were cyclized to the thiadiazoles 199 and thiadiazolines 198, which are of chemotherapeutic interest (80MI8). The aldehyde also affords the expected dimedone derivative 197. 

---