Disaccharide formation using unprotected 2-acetamido sugars as donors, and unprotected glycosides as acceptors^a.

Entry	Donor	Acceptor	Product	Isolated yield of (1→6) linked disaccharide (%)	Regioselectivity/total combined yield
1	GlcNAc 2a			49	(1→6) only
2	GlcNAc 2a			46	(1→6) only
3	GlcNAc 2a			25	3 regioisomers/50%
4	GlcNAc 2a			40e	(1→6) onlye
5	GlcNAc 2a			36	3 regioisomers/48%
6	GlcNAc 2a			33	3 regioisomers/55%
7	GlcNAc 2a			32a	2 regioisomers/46%a
				44b	(1→6) onlyb
8	GlcNAc 2a			39e	(1→6) onlye
9	GlcNAc 2a			31a	3 regioisomers/62%a
				37d	3 regioisomers/54%d
10	GlcNAc 2a			39a	3 regioisomers/68%a
				26b	3 regioisomers/52%b
11	GlcNAc 2a			45	(1→6) < 1% of any other regioisomer
12	GlcNAc 2a			34a	3 regioisomers/47%a
				39b	3 regioisomer/58%b
13	GlcNAc 2a			18	3 regioisomers/51%
14	GalNAc 2b			40	(1→6) only
15	GalNAc 2b			26a	2 regioisomers/40%a
				30c	(1→6) onlyc
16	ManNAc 2c			15	(1→6)/trace amount of another regioisomer

^aReaction conditions: (i) DMC 1, Et₃N, H₂O, 0 °C, 1 h, then freeze-dry; acceptor (3a–i or 5d), MeCN/DMF (10 : 1), 4 Å powdered molecular sieves, TsOH, rt, 3 h.

^bReaction performed at 0 °C.

^cReaction performed at −10 °C.

^dReaction performed at −16 °C for 24 h.

^eReaction performed in DMF as solvent.