Reactions between lithiated 1,3-dithiane oxides and trialkylboranes

Figures & data

Figure 1. 1,3-Dithiane oxide derivatives 1–6.

Figure 2. Structures of 12 and 13.

Scheme 1. Reaction of 3 and trioctylborane to produce nonanoic acid 7.

Scheme 2. Possible rearrangement of the intermediate after the first migration step.

Scheme 3. Reaction of 5 and trioctylborane to produce 9-heptadecanone (dioctyl ketone), 10.

Scheme 4. Pummerer rearrangement induced by TFAA.

Scheme 5. Induction of the third migration via a Pummerer rearrangement.

Scheme 6. A possible mechanism for the formation of 11.

Table 1. The GC yield of 10 according to Scheme 3 but using different lithium reagents.

Entry	Lithium reagent	Mole equivalents	GC Yield of 10 (%)
1	n-BuLi	1.1	16^a
2	tert-BuLi	1.1	12
3	sec-BuLi	1.0	20
4	sec-BuLi	1.1	28
5	sec-BuLi	1.2	31
6	sec-BuLi	1.4	5
7	sec-BuLi	1.8	–
8	LDA	1.1	20
9	LDA	1.1	30^b
10	LDA	5.0	3
11	LiTMP	1.1	12
12	LiHDMS	1.1	18

^a The yield estimated by GC of the crude product mixture is a little higher than that which could be isolated (13%).

^b Reaction conducted at 0°C.