Table 1.

Selective N⁷-acylation of 1.^a

entry	acylating reagent		product	R	yield
1	(CH3CO)2O	3a	2a	Me	78
2	(CH3CH2CO)2O	3b	2b	Et	78
3	(CH3CH2CH2CO)2O	3c	2c	Pr	73
4	[(CH3)2CHCO]2O	3d	2d	iPr	78
5	TBSO(CH2)4COOSu	3e	2e	TBSO(CH2)4	68
6		3f	2f		91

^aCompound 1 was treated with NaH (1.1 equiv) in DMF for 1 h, then an acylating reagent (1.1 equiv) was added. The yields refer to isolated yields.