Note: 2 Corinthians falls into three main section, chs 1-7, chs 8-9 (the collection for the Jerusalem fund) and chs 10-13. A proposal for a chiastic structure for 2-7 appears below. It is posted for challenge. There is no doubt that the letter previously sent by Paul about the problem of immortality in the ecclesia described in chapter 2 is returned to again in chapter 7, and Titus is also mentioned in chs 2 and 7. The remainder of the parallels are not clear to me.
The following is from C Blomberg, Criswell Theological Review 4.1 (1989) 3-20. The Structure of 2 Corinthians 1-7.
A 1:12-22 the Corinthians can rightfully boast in Paul
B 1 :23- 2:11 grief and comfort over the painful letter; hope for forgiving the offender
C 2:12-13 looking for Titus in Macedonia
D 2:14-4:6 a series of contrasts–belief vs. unbelief, centered on Christians as the letters of the living God, in glory being transformed into his image
a 2:14-16a death vs.life
b 2:16b-3:3 false vs true approaches to ministry
c 3:4-18 old covenant vs. new
b’ 4:1-2 false vs. true approaches to ministry
a’ 4:3-6 darkness vs. light
E 4:7-5:10 surviving and triumphing despite every hardship (see esp. vv8-10)
F 5:11-21 the ministry of reconciliation
E’. 6:1-10 surviving and triumphing despite every hardship (see esp. vv.8b-10)
D’. 6:11-7:4 a series of contrasts-belief vs. unbelief, centered on Christians as the temple of the living God, in light being transformed into his holiness
a 6:11-13 widen your hearts
b 6:14-7:1 separate yourselves from uncleanness
a’ 7:2-4 open your hearts
C’. 7:5-7 finding Titus in Macedonia
B’. 7 :8-13a grief and comfort over the painful letter; joy after forgiving the offender
A’ .7:13b-16 Paul can rightfully boast in the Corinthians
Intriguing! I hope to check it out when I get a chance.