Table 1. Polymerization of rac-Lactide with Al Complexes 2a–i^a.

entry	cat.	cat. loading (mol %)	time (h)	conversn (%)b	Mnc	Mnd	Mw/Mnd	Pr/Pme
1	2a	2	24	96	6.92	7.7 (4.4)	1.20	Pr = 0.69
2	2a	0.5	48	97	28.0	12.1 (7.0)	1.45	Pr = 0.51
3	2b	2	24	15
4	2c	2	24	95	6.85	10.8 (6.3)	1.23	Pm = 0.60
5f	2c	2	20	95	6.85	7.7 (4.5)	1.29	Pm = 1.0
6	2d	2	24	12				Pr = 0.53
7	2e	2	24	95	6.85	8.3 (4.8)	1.28	Pr = 0.74
8	2e	1	48	98	14.1	23.6 (13.7)	1.69
9g	2e	1	48	40
10	2f	2	24	12
11	2g	2	24	95	6.85	4.9 (2.8)	1.64	Pm = 0.57
12	2h	2	24	93	6.70	9.7 (5.6)	1.25	Pr = 0.62
13	2i	2	24	98	7.06	9.0 (5.2)	1.53	Pr = 0.61

^aReaction conditions: see the Experimental Section for details.

^bMonomer conversion determined by ¹H NMR spectroscopy.

^cCalculated molecular weight based on conversion: [LA]₀/[Al]₀ × (conversn %) × 144.

^dExperimental molecular weight determined by GPC vs polystyrene standards. The values in parentheses are corrected by a factor of 0.58.²³

^eProbability of racemic (P_r) or meso (P_m) enchainment, determined by homonuclear decoupled ¹H NMR spectroscopy.

^fl-Lactide was used.

^gReaction was carried out in THF at 60 °C.