3- or 4′′-Acylated derivatives of spiramycin I.

Acylation conditions: (1) acyl chloride, DMAP, Et3N, DCM; (2) acid, DCC, 4-PPY, DMF; (3) isocyanates, Et3N, DMF
Cmpd	R1	R2	Cmpd	R1	R2
1		H	2		H
3		H	4		H
5		H	6		H
7		H	8		H
9a		H	9b	H
10a		H	10b	H
11		H	12		H
13		H	14		H
15		H	16		H
17		H	18		H
19		H	20		H