F-butoxycarbonyl protecting

The protecting reaction of the enamino pyrrolidinone with t-butoxycarbonyl anhydride was carried out by mixing 4-(N-/-butoxycarbonyl)-4-aminomethylene-pyirolidin-3-one (Boc-AMP) with 1.2 molar equivalents of t-butoxycarbonyl anhydride (/-BoczO) to make l-(N-f-butoxycarbonyl)-4-(N-t-butoxycarbonyl)-ammomethylene-pyrrolidin-3-one (B0C2-AMP). Several types of reactors, including batch reactors, a continuous stirred tank reactor (CSTR),... 

Highly substituted pyrrolo[l,2- ][l,2,4]triazines were synthesized from pyrrole derivatives, by closure of the triazine ring. Thus, hydrolytic cleavage of some 1,2-diaminopyrroles having a 1-NH-BOC-protected amino function 43 followed by reaction with 1,2-dicarbonyl compounds afforded a one-pot access to the corresponding bicyclic heterocycles 44 (BOC = f-butoxycarbonyl Equation 6) < 1997J(P 1)1829>. 

Modern methods of peptide synthesis began with the solid-phase method introduced by Merrifield299 in 1962 (Fig. 3-15). To begin the synthesis a suitably protected amino acid is covalently linked to a polystyrene bead. The blocking f-butoxycarbonyl (Boc) group is removed as isobutene by an elimination reaction to give a bound amino acid with a free amino group. 

Know the meaning of protecting group, solid-phase technique, f-butoxycarbonyl (Boc) group, dicyclohexylcarbodiimide (DCC). 

The Z group can be hydrogenolyzed in the presence of other protective groups such as f-butyl ester, f-butyl ether, and iV-f-butoxycarbonyl (Boc) groups. f-Butyl esters are not affected by hydrogenation in the presence of palladium or platinum and are much more readily removed by acid catalysis (eq. 13.31).65... 

Protection of allylic amines with a f-butoxycarbonyl (Boc),benzyloxycar-bonyl (Cbz), or p-methoxybenzyloxycarbonyl (PMB) group furnished the desired 9-BBN derivative for the coupling reaction [106, 107, 119]. The alkyl-vinyl and alkyl-aryl coupling reactions readily proceed on the solid-phase which was demonstrated in the preparation of members of several structurally distinct PG classes (47) [120]. 

N-f-butoxycarbonyl group (e.g., 25% HBr-HOAc, TFA-anisole), but is removed by TFA in the presence of dimethyl sulfide within 40-60 minutes at 23°. The N -tosyl protecting group is also removed under these conditions, but at a slower rate. The p-methoxysulfonyl group is also removed by N-hydroxybenzotriazole or by 1 Af NaOH within 1 hour, but only partially by 80% hydrazine hydrate after 24 hours. 

Isoxazolines have also been converted into 1,3-amino alcohols by polymethylhydrosiloxane (PMHS)-Pd(OH)2/C. When the reduction was performed in the presence of (B0C)20, WBOC protected compounds were directly achieved (BOC = f-butoxycarbonyl). For example, WBOG-y-amino alcohols 132 were synthesized from the corresponding isoxazolines 131 in one step and 78-88% yield (Equation 15) <2004SL1303>. 

In fact, this case has been extensively studied and we consider it in more detail in Part B, Chapter 2. An example is the condensation of the enolate of a derivative of pyroglutamic acid and a protected form of glyceraldehyde. In the case of the (R)-aldehyde a single enantiomer is formed, whereas with the (5)-aldehyde a 1 1 mixture of two diastereomers is formed, along with a small amount of a third diastereomer2 The facial preference of the enolate is determined by the steric effect of the f-butoxycarbonyl group, whereas in the aldehyde the Felkin-Ahn TS prefers an approach anti to the a-oxygen. 

Temporary protection of a-amino acid facilitates certain transformations, includii isocyanate. Thus, Fmoc-derivatives of t a-isocyanatocarboxylic esters on reaction When de-Af-(f-butoxycarbonylation 1 is cat Selective reaction of the primary amm trimethylsilylation of both has been demot still derivatizable. 

Aminothiophene and 3-aminobenzo[A]thiophene, in which the amino group is protected by either the trifluoroacetyl group or by the f-butoxycarbonyl group, have been shown to give the N,C-2 dianions on treatment with 3.2 equiv. of -BuLi at —20°C <92JOC2l84). 

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