Table 3. Homodimerization of Canonical Amino Acids for Investigating Side-Chain Influence on Catalytic Activity.

			yielda (%)		Z selectivityb (%)
entry	amino acid	product	1	2	1	2
1	valine (5a)	6a	74	71	90	94
2	isoleucine (5b)	6b	68	72	88	92
3	leucine (5c)	6c	70	71	88	91
4	phenylalanine (5d)	6d	73	75	89	93
5	glycine (5e)	6e	<10	<10	n.d.	n.d.
6	proline (5f)	6f	<10	<5	n.d.	n.d.
7	tryptophan (5g)	6g	66	64	85	90
8	histidine (5h)	6h	<5	<5	n.d.	n.d.
9	serine (5i)	6i	72	70	84	90
10	threonine (5j)	6i	73	70	88	92
11	tyrosine (5k)	6k	64	68	87	90
12	methionine (51)	61	<5	<10	n.d.	n.d.
13	cysteine (5m)c	6m	55	53	87	92
14	aspartic acid (5n)d	6n	61	60	87	90
15	glutamic acid (5o)d	6o	74	71	88	91
16	asparagine (5p)c	6p	70	71	88	91
17	glutamine (5q)c	6q	74	74	88	91
18	lysine (5r)e	6r	78	81	81	89
19	arginine (5s)e	6s	34	33	81	89

^aIsolated yields.

^bDetermined by ¹H or ¹³C NMR spectroscopy.

^cSide chain protected with a trityl group.

^dSide chain protected as the t-butyl ester.

^eSide chain protected as the t-butyl carbamate.

^eSide chain protected with 2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl (Pbf).